[COMMITTED] Robustify Linux kernel headers configure checks

--- a/sysdeps/unix/sysv/linux/configure
+++ b/sysdeps/unix/sysv/linux/configure
@@ -37,137 +37,6 @@  if test -n "$sysheaders"; then
   CPPFLAGS="$CPPFLAGS $SYSINCLUDES"
 fi
 
-
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for grep that handles long lines and -e" >&5
-$as_echo_n "checking for grep that handles long lines and -e... " >&6; }
-if ${ac_cv_path_GREP+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  if test -z "$GREP"; then
-  ac_path_GREP_found=false
-  # Loop through the user's path and test for each of PROGNAME-LIST
-  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH$PATH_SEPARATOR/usr/xpg4/bin
-do
-  IFS=$as_save_IFS
-  test -z "$as_dir" && as_dir=.
-    for ac_prog in grep ggrep; do
-    for ac_exec_ext in '' $ac_executable_extensions; do
-      ac_path_GREP="$as_dir/$ac_prog$ac_exec_ext"
-      { test -f "$ac_path_GREP" && $as_test_x "$ac_path_GREP"; } || continue
-# Check for GNU ac_path_GREP and select it if it is found.
-  # Check for GNU $ac_path_GREP
-case `"$ac_path_GREP" --version 2>&1` in
-*GNU*)
-  ac_cv_path_GREP="$ac_path_GREP" ac_path_GREP_found=:;;
-*)
-  ac_count=0
-  $as_echo_n 0123456789 >"conftest.in"
-  while :
-  do
-    cat "conftest.in" "conftest.in" >"conftest.tmp"
-    mv "conftest.tmp" "conftest.in"
-    cp "conftest.in" "conftest.nl"
-    $as_echo 'GREP' >> "conftest.nl"
-    "$ac_path_GREP" -e 'GREP$' -e '-(cannot match)-' < "conftest.nl" >"conftest.out" 2>/dev/null || break
-    diff "conftest.out" "conftest.nl" >/dev/null 2>&1 || break
-    as_fn_arith $ac_count + 1 && ac_count=$as_val
-    if test $ac_count -gt ${ac_path_GREP_max-0}; then
-      # Best one so far, save it but keep looking for a better one
-      ac_cv_path_GREP="$ac_path_GREP"
-      ac_path_GREP_max=$ac_count
-    fi
-    # 10*(2^10) chars as input seems more than enough
-    test $ac_count -gt 10 && break
-  done
-  rm -f conftest.in conftest.tmp conftest.nl conftest.out;;
-esac
-
-      $ac_path_GREP_found && break 3
-    done
-  done
-  done
-IFS=$as_save_IFS
-  if test -z "$ac_cv_path_GREP"; then
-    as_fn_error $? "no acceptable grep could be found in $PATH$PATH_SEPARATOR/usr/xpg4/bin" "$LINENO" 5
-  fi
-else
-  ac_cv_path_GREP=$GREP
-fi
-
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_path_GREP" >&5
-$as_echo "$ac_cv_path_GREP" >&6; }
- GREP="$ac_cv_path_GREP"
-
-
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for egrep" >&5
-$as_echo_n "checking for egrep... " >&6; }
-if ${ac_cv_path_EGREP+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  if echo a | $GREP -E '(a|b)' >/dev/null 2>&1
-   then ac_cv_path_EGREP="$GREP -E"
-   else
-     if test -z "$EGREP"; then
-  ac_path_EGREP_found=false
-  # Loop through the user's path and test for each of PROGNAME-LIST
-  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH$PATH_SEPARATOR/usr/xpg4/bin
-do
-  IFS=$as_save_IFS
-  test -z "$as_dir" && as_dir=.
-    for ac_prog in egrep; do
-    for ac_exec_ext in '' $ac_executable_extensions; do
-      ac_path_EGREP="$as_dir/$ac_prog$ac_exec_ext"
-      { test -f "$ac_path_EGREP" && $as_test_x "$ac_path_EGREP"; } || continue
-# Check for GNU ac_path_EGREP and select it if it is found.
-  # Check for GNU $ac_path_EGREP
-case `"$ac_path_EGREP" --version 2>&1` in
-*GNU*)
-  ac_cv_path_EGREP="$ac_path_EGREP" ac_path_EGREP_found=:;;
-*)
-  ac_count=0
-  $as_echo_n 0123456789 >"conftest.in"
-  while :
-  do
-    cat "conftest.in" "conftest.in" >"conftest.tmp"
-    mv "conftest.tmp" "conftest.in"
-    cp "conftest.in" "conftest.nl"
-    $as_echo 'EGREP' >> "conftest.nl"
-    "$ac_path_EGREP" 'EGREP$' < "conftest.nl" >"conftest.out" 2>/dev/null || break
-    diff "conftest.out" "conftest.nl" >/dev/null 2>&1 || break
-    as_fn_arith $ac_count + 1 && ac_count=$as_val
-    if test $ac_count -gt ${ac_path_EGREP_max-0}; then
-      # Best one so far, save it but keep looking for a better one
-      ac_cv_path_EGREP="$ac_path_EGREP"
-      ac_path_EGREP_max=$ac_count
-    fi
-    # 10*(2^10) chars as input seems more than enough
-    test $ac_count -gt 10 && break
-  done
-  rm -f conftest.in conftest.tmp conftest.nl conftest.out;;
-esac
-
-      $ac_path_EGREP_found && break 3
-    done
-  done
-  done
-IFS=$as_save_IFS
-  if test -z "$ac_cv_path_EGREP"; then
-    as_fn_error $? "no acceptable egrep could be found in $PATH$PATH_SEPARATOR/usr/xpg4/bin" "$LINENO" 5
-  fi
-else
-  ac_cv_path_EGREP=$EGREP
-fi
-
-   fi
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_path_EGREP" >&5
-$as_echo "$ac_cv_path_EGREP" >&6; }
- EGREP="$ac_cv_path_EGREP"
-
-
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking installed Linux kernel header files" >&5
 $as_echo_n "checking installed Linux kernel header files... " >&6; }
 if ${libc_cv_linux2632+:} false; then :
@@ -177,17 +46,22 @@  else
 /* end confdefs.h.  */
 #include <linux/version.h>
 #if !defined LINUX_VERSION_CODE || LINUX_VERSION_CODE <  (2 *65536+ 6 *256+ 32) /* 2.6.32 */
-eat flaming death
+# error kernel headers missing or too old
 #endif
+int
+main ()
+{
+
+  ;
+  return 0;
+}
 _ACEOF
-if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
-  $EGREP "eat flaming death" >/dev/null 2>&1; then :
-  libc_cv_linux2632='TOO OLD!'
-else
+if ac_fn_c_try_compile "$LINENO"; then :
   libc_cv_linux2632='2.6.32 or later'
+else
+  libc_cv_linux2632='missing or too old!'
 fi
-rm -f conftest*
-
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_linux2632" >&5
 $as_echo "$libc_cv_linux2632" >&6; }
@@ -231,17 +105,22 @@  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 #include <linux/version.h>
 #if LINUX_VERSION_CODE < $decnum
-eat flaming death
+# error kernel headers too old
 #endif
+int
+main ()
+{
+
+  ;
+  return 0;
+}
 _ACEOF
-if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
-  $EGREP "eat flaming death" >/dev/null 2>&1; then :
-  libc_minimum_kernel='too old!'
-else
+if ac_fn_c_try_compile "$LINENO"; then :
   libc_minimum_kernel=ok
+else
+  libc_minimum_kernel='too old!'
 fi
-rm -f conftest*
-
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_minimum_kernel" >&5
 $as_echo "$libc_minimum_kernel" >&6; }
 if test "$libc_minimum_kernel" = ok; then
--- a/sysdeps/unix/sysv/linux/configure.ac
+++ b/sysdeps/unix/sysv/linux/configure.ac
@@ -8,14 +8,14 @@  if test -n "$sysheaders"; then
 fi
 define([libc_cv_linuxVER], [libc_cv_linux]patsubst(LIBC_LINUX_VERSION,[\.]))dnl
 AC_CACHE_CHECK(installed Linux kernel header files, libc_cv_linuxVER, [dnl
-AC_EGREP_CPP([eat flaming death], [#include <linux/version.h>
+AC_TRY_COMPILE([#include <linux/version.h>
 #if !defined LINUX_VERSION_CODE || LINUX_VERSION_CODE < ]dnl
 patsubst(LIBC_LINUX_VERSION,[^\([^.]*\)\.\([^.]*\)\.\([^.]*\)$],dnl
 [ (\1 *65536+ \2 *256+ \3) /* \1.\2.\3 */])[
-eat flaming death
-#endif],
-	     libc_cv_linuxVER='TOO OLD!',
-	     libc_cv_linuxVER='LIBC_LINUX_VERSION or later')])
+# error kernel headers missing or too old
+#endif], [],
+	       [libc_cv_linuxVER='LIBC_LINUX_VERSION or later'],
+	       [libc_cv_linuxVER='missing or too old!'])])
 if test "$libc_cv_linuxVER" != 'LIBC_LINUX_VERSION or later'; then
   AC_MSG_ERROR([GNU libc requires kernel header files from
 Linux LIBC_LINUX_VERSION or later to be installed before configuring.
@@ -52,10 +52,10 @@  changequote(,)dnl
 decnum=`echo "$minimum_kernel.0.0.0" | sed 's/\([0-9]*\)\.\([0-9]*\)\.\([0-9]*\).*/(\1 * 65536 + \2 * 256 + \3)/'`;
 abinum=`echo "$minimum_kernel.0.0.0" | sed 's/\([0-9]*\)\.\([0-9]*\)\.\([0-9]*\).*/\1,\2,\3/'`;
 changequote([,])dnl
-AC_EGREP_CPP([eat flaming death], [#include <linux/version.h>
+AC_TRY_COMPILE([#include <linux/version.h>
 #if LINUX_VERSION_CODE < $decnum
-eat flaming death
-#endif], libc_minimum_kernel='too old!', libc_minimum_kernel=ok)
+# error kernel headers too old
+#endif], [], [libc_minimum_kernel=ok], [libc_minimum_kernel='too old!'])
 AC_MSG_RESULT($libc_minimum_kernel)
 if test "$libc_minimum_kernel" = ok; then
   AC_DEFINE_UNQUOTED(__LINUX_KERNEL_VERSION, $decnum)