Replace regex files with multibyte-aware version from FreeBSD.

	Replace regex files with multibyte-aware version from FreeBSD.
	* Makefile.in (install-headers): Remove extra command to install
	regex.h.
	(uninstall-headers): Remove extra command to uninstall regex.h.
	* nlsfuncs.cc (collate_lcid): Make externally available to allow
	access to collation internals from regex functions.
	(collate_charset): Ditto.
	* wchar.h: Add __cplusplus guards to make C-clean.
	* include/regex.h: New file, replacing regex/regex.h.  Remove UCB
	advertising clause.
	* regex/COPYRIGHT: Accommodate BSD license.  Remove UCB advertising
	clause.
	* regex/cclass.h: Remove.
	* regex/cname.h: New file from FreeBSD.
	* regex/engine.c: Ditto.
	(NONCHAR): Tweak for Cygwin.
	* regex/engine.ih: Remove.
	* regex/mkh: Remove.
	* regex/regcomp.c: New file from FreeBSD.  Tweak slightly for Cygwin.
	Import required collate internals from nlsfunc.cc.
	(p_ere_exp): Add GNU-specific \< and \> handling for word boundaries.
	(p_simp_re): Ditto.
	(__collate_range_cmp): Define.
	(p_b_term): Use Cygwin-specific collate internals.
	(findmust): Ditto.
	* regex/regcomp.ih: Remove.
	* regex/regerror.c: New file from FreeBSD.  Fix a few compiler warnings.
	* regex/regerror.ih: Remove.
	* regex/regex.7: New file from FreeBSD.  Remove UCB advertising clause.
	* regex/regex.h: Remove.  Replaced by include/regex.h.
	* regex/regexec.c: New file from FreeBSD.  Fix a few compiler warnings.
	* regex/regfree.c: New file from FreeBSD.
	* regex/tests: Remove.
	* regex/utils.h: New file from FreeBSD.