Port exclude.c and exclude.h to more non-GNU systems, e.g. Solaris 7.
(FNM_CASEFOLD, FNM_LEADING_DIR): Define to 0 if not
defined (e.g., a pure POSIX system).
(EXCLUDE_macros_do_not_collide_with_FNM_macros): Use FNM_PATHNAME
instead of FNM_FILE_NAME, for compatibility with pure POSIX sytems.
This fixes one or two unlikely storage allocation overflow bugs,
but doesn't change user-visible behavior otherwise.
(bool): Declare, perhaps by including stdbool.h.
(<sys/types.h>): Include only if HAVE_SYS_TYPES_H.
(<stdlib.h>, <string.h>, <strings.h>, <inttypes.h>, <stdint.h>):
Include if available.
(<xalloc.h>): Include
(SIZE_MAX): Define if <stdint.h> or <inttypes.h> doesn't.
(verify): New macro. Use it to verify that EXCLUDE macros do not
collide with FNM macros.
(struct patopts): New struct.
(struct exclude): Use it, as exclude patterns now come with options.
(new_exclude): Support above changes.
(new_exclude, add_exclude_file):
Initial size must now be a power of two to simplify overflow checking.
(free_exclude, fnmatch_no_wildcards): New function.
(excluded_filename): No longer requires options arg, as the options
are determined by add_exclude. Now returns bool, not int.
(excluded_filename, add_exclude):
Add support for the fancy new exclusion options.
(add_exclude, add_exclude_file): Now takes int options arg.
Check for arithmetic overflow when computing sizes.
(add_exclude_file): xrealloc might modify errno, so don't
realloc until after errno might be used.
