[COMMITTED] Fix spelling and grammar in several comments

diff --git a/argp/argp.h b/argp/argp.h
index a5b861a4d3..2cbc4dcb1b 100644
--- a/argp/argp.h
+++ b/argp/argp.h
@@ -1,4 +1,4 @@ 
-/* Hierarchial argument parsing, layered over getopt.
+/* Hierarchical argument parsing, layered over getopt.
    Copyright (C) 1995-2020 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Written by Miles Bader <miles@gnu.ai.mit.edu>.
@@ -233,7 +233,7 @@  struct argp
 };
 
 /* Possible KEY arguments to a help filter function.  */
-#define ARGP_KEY_HELP_PRE_DOC	0x2000001 /* Help text preceeding options. */
+#define ARGP_KEY_HELP_PRE_DOC	0x2000001 /* Help text preceding options. */
 #define ARGP_KEY_HELP_POST_DOC	0x2000002 /* Help text following options. */
 #define ARGP_KEY_HELP_HEADER	0x2000003 /* Option header string. */
 #define ARGP_KEY_HELP_EXTRA	0x2000004 /* After all other documentation;
@@ -447,7 +447,7 @@  extern void __argp_help (const struct argp *__restrict __argp,
    parsing routine (thus taking an argp_state structure as the first
    argument).  They may or may not print an error message and exit, depending
    on the flags in STATE -- in any case, the caller should be prepared for
-   them *not* to exit, and should return an appropiate error after calling
+   them *not* to exit, and should return an appropriate error after calling
    them.  [argp_usage & argp_error should probably be called argp_state_...,
    but they're used often enough that they should be short]  */
 
diff --git a/inet/aliases.h b/inet/aliases.h
index b22ed63831..5722e9d0da 100644
--- a/inet/aliases.h
+++ b/inet/aliases.h
@@ -25,7 +25,7 @@ 
 
 __BEGIN_DECLS
 
-/* Structure to represent one entry of the alias data base.  */
+/* Structure to represent one entry of the alias database.  */
 struct aliasent
   {
     char *alias_name;
@@ -38,13 +38,13 @@  struct aliasent
 /* Open alias data base files.  */
 extern void setaliasent (void) __THROW;
 
-/* Close alias data base files.  */
+/* Close alias database files.  */
 extern void endaliasent (void) __THROW;
 
-/* Get the next entry from the alias data base.  */
+/* Get the next entry from the alias database.  */
 extern struct aliasent *getaliasent (void) __THROW;
 
-/* Get the next entry from the alias data base and put it in RESULT_BUF.  */
+/* Get the next entry from the alias database and put it in RESULT_BUF.  */
 extern int getaliasent_r (struct aliasent *__restrict __result_buf,
 			  char *__restrict __buffer, size_t __buflen,
 			  struct aliasent **__restrict __result) __THROW;
diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h
index e94d09d7dd..a06f1cfd91 100644
--- a/misc/sys/cdefs.h
+++ b/misc/sys/cdefs.h
@@ -25,7 +25,7 @@ 
 
 /* The GNU libc does not support any K&R compilers or the traditional mode
    of ISO C compilers anymore.  Check for some of the combinations not
-   anymore supported.  */
+   supported anymore.  */
 #if defined __GNUC__ && !defined __STDC__
 # error "You need a ISO C conforming compiler to use the glibc headers"
 #endif
@@ -47,7 +47,7 @@ 
 # endif
 
 /* GCC can always grok prototypes.  For C++ programs we add throw()
-   to help it optimize the function calls.  But this works only with
+   to help it optimize the function calls.  But this only works with
    gcc 2.8.x and egcs.  For gcc 3.2 and up we even mark C functions
    as non-throwing using a function attribute since programs can use
    the -fexceptions options for C code as well.  */
diff --git a/stdlib/alloca.h b/stdlib/alloca.h
index bd44688720..be915737c6 100644
--- a/stdlib/alloca.h
+++ b/stdlib/alloca.h
@@ -25,7 +25,7 @@ 
 
 __BEGIN_DECLS
 
-/* Remove any previous definitions.  */
+/* Remove any previous definition.  */
 #undef	alloca
 
 /* Allocate a block that will be freed when the calling function exits.  */
diff --git a/sysdeps/unix/sysv/linux/net/ethernet.h b/sysdeps/unix/sysv/linux/net/ethernet.h
index f98c27c028..7ec796155a 100644
--- a/sysdeps/unix/sysv/linux/net/ethernet.h
+++ b/sysdeps/unix/sysv/linux/net/ethernet.h
@@ -56,7 +56,6 @@  struct ether_header
 #define	ETHERTYPE_IPV6		0x86dd		/* IP protocol version 6 */
 #define ETHERTYPE_LOOPBACK	0x9000		/* used to test interfaces */
 
-
 #define	ETHER_ADDR_LEN	ETH_ALEN                 /* size of ethernet addr */
 #define	ETHER_TYPE_LEN	2                        /* bytes in type field */
 #define	ETHER_CRC_LEN	4                        /* bytes in CRC field */
@@ -64,7 +63,7 @@  struct ether_header
 #define	ETHER_MIN_LEN	(ETH_ZLEN + ETHER_CRC_LEN) /* min packet length */
 #define	ETHER_MAX_LEN	(ETH_FRAME_LEN + ETHER_CRC_LEN) /* max packet length */
 
-/* make sure ethenet length is valid */
+/* make sure ethernet length is valid */
 #define	ETHER_IS_VALID_LEN(foo)	\
 	((foo) >= ETHER_MIN_LEN && (foo) <= ETHER_MAX_LEN)