Installed-header hygiene (BZ#20366): Simple self-contained fixes.

Some headers did not include all of their prerequisite headers.

	* rpcsvc/nislib.h: Include rpcsvc/nis.h.
	* sysdeps/unix/sysv/linux/netrose/rose.h:
	Include sys/socket.h and netax25/ax25.h.

<endian.h> only defines BYTE_ORDER, BIG_ENDIAN, LITTLE_ENDIAN,
etc. under __USE_MISC; glibc's headers should use __BYTE_ORDER,
__BIG_ENDIAN, __LITTLE_ENDIAN, etc. instead.

	* inet/netinet/icmp6.h, inet/netinet/ip6.h
	* resolv/arpa/nameser_compat.h:
	Use __BYTE_ORDER etc. instead of BYTE_ORDER etc.

sys/types.h only conditionally defines caddr_t and clockid_t.

	* sysdeps/unix/sysv/linux/sys/quota.h:
	Use __caddr_t instead of caddr_t.
	* sysdeps/unix/sysv/linux/sys/timerfd.h:
	Use __clockid_t instead of clockid_t.

Remove a #warning that was the sole actual problem with using sys/ipc.h
without _GNU_SOURCE/_XOPEN_SOURCE.

	* sysvipc/sys/ipc.h: Remove unnecessary #warning.

_LIBC, __USE_XOPEN2K8, and __STDC_VERSION__ are not always defined.

It seems to me that _LIBC should not appear in installed headers, but
avoiding that for argp specifically would require more surgery than
feels appropriate for this patch set.  It's possible that
"#ifdef _LIBC" would be sufficient, but I wanted to be conservative.

All three versions of bits/socket.h want to know whether __flexarr
will produce a real flexible array member -- specifically, one that
doesn't alter sizeof(the structure containing it).  They were testing
for this with a complicated #if condition that did not agree with
sys/cdefs.h and that tripped -Wundef warnings under -std=c90.
I added a new macro to sys/cdefs.h, __glibc_c99_flexarr_available,
which reveals exactly what these headers want to know.  I also took
the opportunity to flatten the rather messy conditional nest defining
__flexarr.

	* argp/argp.h: Check whether _LIBC is defined before expanding it.
	* posix/glob.h: Check whether __USE_XOPEN2K8 is defined instead
	of expanding it.

	* misc/sys/cdefs.h: Tidy up conditional nest defining __flexarr.
	Define __glibc_c99_flexarr_available to 1 when the compiler
	supports C99-compatible flexible array members, 0 otherwise.
	* sysdeps/unix/sysv/linux/bits/socket.h
	* sysdeps/mach/hurd/bits/socket.h
	* bits/socket.h: Use __glibc_c99_flexarr_available in
	definitions of struct cmsghdr and CMSG_DATA.

1 files changed, 18 insertions, 12 deletions

diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h
index 6e9b8403d7..935a94b466 100644
--- a/misc/sys/cdefs.h
+++ b/misc/sys/cdefs.h
@@ -153,21 +153,27 @@
 # define __errordecl(name, msg) extern void name (void)
 #endif
 
-/* Support for flexible arrays.  */
-#if __GNUC_PREREQ (2,97)
-/* GCC 2.97 supports C99 flexible array members.  */
+/* Support for flexible arrays.
+   Headers that should use flexible arrays only if they're "real"
+   (e.g. only if they won't affect sizeof()) should test
+   #if __glibc_c99_flexarr_available.  */
+#if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
+# define __flexarr	[]
+# define __glibc_c99_flexarr_available 1
+#elif __GNUC_PREREQ (2,97)
+/* GCC 2.97 supports C99 flexible array members as an extension,
+   even when in C89 mode or compiling C++ (any version).  */
 # define __flexarr	[]
+# define __glibc_c99_flexarr_available 1
+#elif defined __GNUC__
+/* Pre-2.97 GCC did not support C99 flexible arrays but did have
+   an equivalent extension with slightly different notation.  */
+# define __flexarr	[0]
+# define __glibc_c99_flexarr_available 1
 #else
-# ifdef __GNUC__
-#  define __flexarr	[0]
-# else
-#  if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
-#   define __flexarr	[]
-#  else
 /* Some other non-C99 compiler.  Approximate with [1].  */
-#   define __flexarr	[1]
-#  endif
-# endif
+# define __flexarr	[1]
+# define __glibc_c99_flexarr_available 0
 #endif