[PATCH 2/3] Modernize AC_INCLUDES_DEFAULT and friends.

[Zack Weinberg]

 * lib/autoconf/headers.m4 (_AC_INCLUDES_DEFAULT_REQUIREMENTS):
   Include stddef.h, stdlib.h, and string.h unconditionally.
   Don't include memory.h at all.
   Don't use AC_HEADER_STDC.
   Don't check for stddef.h, stdlib.h, string.h, or memory.h.
   For compatibility, unconditionally define STDC_HEADERS,
   HAVE_STDLIB_H, and HAVE_STRING_H.
   (AN_HEADER list): Remove C89 headers, and memory.h from list.
   (AC_HEADER_STDC): AU_DEFUN as an explicit invocation of
   _AC_INCLUDES_DEFAULT_REQUIREMENTS.
   (AC_HEADER_TIME): AU_DEFUN, and define TIME_WITH_SYS_TIME unconditionally
   as long as sys/time.h is present.
   (AC_USG, AC_MEMORY_H): Assume existence of string.h.
 * lib/autoconf/functions.m4 (_AC_FUNC_MALLOC_IF, _AC_FUNC_REALLOC_IF):
   Don't use AC_HEADER_STDC. Assume stdlib.h exists.
   (AC_FUNC_MKTIME): Don't use AC_HEADER_TIME.
   (AC_FUNC_ALLOCA): Assume stdlib.h exists.
   (_AC_LIBOBJ_FNMATCH): Assume wchar.h and wctype.h exist.
   (_AC_LIBOBJ_GETLOADAVG): Assume locale.h exists.
   (AC_FUNC_MMAP): Assume stdlib.h exists.
 * tests/tools.at: Use AC_WORDS_BIGENDIAN instead of AC_STDC_HEADERS in
   autoupdate test.

 * NEWS, doc/autoconf.texi: Document changes. Remove obsolete advice.

Signed-off-by: Zack Weinberg <address@hidden>
---
 NEWS                      |   24 ++++
 doc/autoconf.texi         |  314 +++++++++++++++++----------------------------
 lib/autoconf/functions.m4 |   35 +----
 lib/autoconf/headers.m4   |  179 ++++++++++----------------
 tests/tools.at            |    6 +-
 5 files changed, 218 insertions(+), 340 deletions(-)

0002-Modernize-AC_INCLUDES_DEFAULT-and-friends.patch
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