posix: Use enum for __glob_pattern_type result

This patch replaces the internal integer constant from
__glob_pattern_type return with a proper enum.

Checked on x86_64-linux-gnu and on a build using build-many-glibcs.py
for all major architectures.

	* posix/glob_internal.h (glob_pattern_type_t): New enumeration.
	(__glob_pattern_type): Use __glob_pat_types.
	* posix/glob_pattern_p.c (__glob_pattern_p): Likewise.
	* posix/glob.c (glob): Likewise.
	(glob_in_dir): Likewise.