Don't use IFUNC resolver for longjmp or system in libpthread (bug 21041)

diff --git a/nptl/Makefile b/nptl/Makefile
index 128a52eadc..9925f0f745 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -367,7 +367,7 @@  tests += tst-cancelx2 tst-cancelx3 tst-cancelx4 tst-cancelx5 \
 	 tst-cleanupx0 tst-cleanupx1 tst-cleanupx2 tst-cleanupx3 tst-cleanupx4 \
 	 tst-oncex3 tst-oncex4
 ifeq ($(build-shared),yes)
-tests += tst-atfork2 tst-tls4 tst-_res1 tst-fini1
+tests += tst-atfork2 tst-tls4 tst-_res1 tst-fini1 tst-compat-forwarder
 tests-internal += tst-tls3 tst-tls3-malloc tst-tls5 tst-stackguard1
 tests-nolibpthread += tst-fini1
 ifeq ($(have-z-execstack),yes)
@@ -379,7 +379,7 @@  modules-names = tst-atfork2mod tst-tls3mod tst-tls4moda tst-tls4modb \
 		tst-tls5mod tst-tls5moda tst-tls5modb tst-tls5modc \
 		tst-tls5modd tst-tls5mode tst-tls5modf tst-stack4mod \
 		tst-_res1mod1 tst-_res1mod2 tst-execstack-mod tst-fini1mod \
-		tst-join7mod
+		tst-join7mod tst-compat-forwarder-mod
 extra-test-objs += $(addsuffix .os,$(strip $(modules-names))) \
 		   tst-cleanup4aux.o tst-cleanupx4aux.o
 test-extras += tst-cleanup4aux tst-cleanupx4aux
@@ -718,6 +718,8 @@  $(objpfx)tst-oddstacklimit.out: $(objpfx)tst-oddstacklimit $(objpfx)tst-basic1
 	$(evaluate-test)
 endif
 
+$(objpfx)tst-compat-forwarder: $(objpfx)tst-compat-forwarder-mod.so
+
 # The tests here better do not run in parallel
 ifneq ($(filter %tests,$(MAKECMDGOALS)),)
 .NOTPARALLEL:
diff --git a/nptl/tst-compat-forwarder-mod.c b/nptl/tst-compat-forwarder-mod.c
new file mode 100644
index 0000000000..823bfa22de
--- /dev/null
+++ b/nptl/tst-compat-forwarder-mod.c
@@ -0,0 +1,28 @@ 
+/* Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Call the function system through a statically initialized pointer.  */
+
+#include <stdlib.h>
+
+int (*system_function) (const char *) = system;
+
+void
+call_system (void)
+{
+  system_function (NULL);
+}
diff --git a/nptl/tst-compat-forwarder.c b/nptl/tst-compat-forwarder.c
new file mode 100644
index 0000000000..f96806b7fe
--- /dev/null
+++ b/nptl/tst-compat-forwarder.c
@@ -0,0 +1,35 @@ 
+/* Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Test that the compat forwaders in libpthread work correctly.  */
+
+#include <support/test-driver.h>
+
+extern void call_system (void);
+
+int
+do_test (void)
+{
+  /* Calling the system function from a shared library that is not linked
+     against libpthread, when the main program is linked against
+     libpthread, should not crash.  */
+  call_system ();
+
+  return 0;
+}
+
+#include <support/test-driver.c>