glob-h: New module.

glob-h: New module.

* lib/glob.in.h: Use nearly the usual gnulib idioms for header file
replacements.
* lib/glob.c: Include <config.h>.
* m4/glob_h.m4: New file.
* m4/glob.m4 (gl_GLOB): Require gl_GLOB_H. Remove code that is moved to
glob_h.m4. Set HAVE_GLOB, REPLACE_GLOB, HAVE_GLOB_PATTERN_P,
REPLACE_GLOB_PATTERN_P as appropriate.
(gl_PREREQ_GLOB): Don't require AC_C_RESTRICT and
AC_USE_SYSTEM_EXTENSIONS, now done through module 'glob-h'.
* modules/glob-h: New file.
* modules/glob (Files): Remove lib/glob.in.h, lib/glob-libc.h.
(Dependencies): Add glob-h. Remove extensions, snippet/*, libc-config,
lstat, sys_stat. Change conditions.
(configure.ac): Test HAVE_GLOB, REPLACE_GLOB, HAVE_GLOB_PATTERN_P,
REPLACE_GLOB_PATTERN_P. Set module indicator.
(Makefile.am): Remove code that is moved to glob-h.
* doc/posix-headers/glob.texi: Mention the 'glob-h' module.
* modules/posixcheck (Depends-on): Add glob-h.