POSIX-1.2008 per-thread locales, groundwork part 1

Introduce first cut of struct _thr_locale_t used for the locale_t definition.
Introduce global instance called __global_locale used by default.
Introduce internal inline functions __get_global_locale, __get_locale_r,
__get_current_locale.

Remove usage of global variables in favor of accessor functions pointing to
__global_locale for now.  Include all local headers in locale subdir from
setlocale.h to get single include for internal locale access.

Introduce __CTYPE_PTR macro to replace direct access to __ctype_ptr__
and use throughout in isxxx functions.

Signed-off by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/regex/regcomp.c

@@ -63,9 +63,8 @@ __FBSDID("$FreeBSD: src/lib/libc/regex/regcomp.c,v 1.36 2007/06/11 03:05:54 delp
 #include "cname.h"
 
 #ifdef __CYGWIN__
-/* These are defined in nlsfuncs.cc. */
-extern LCID collate_lcid;
-extern char collate_charset[];
+/* Defined in nlsfuncs.cc. */
+extern LCID __get_current_collate_lcid ();
 #endif
 
 /*
@@ -832,7 +831,7 @@ p_b_term(struct parse *p, cset *cs)
 			CHadd(p, cs, start);
 		else {
 #ifdef __CYGWIN__
-			if (!collate_lcid) {
+			if (!__get_current_collate_lcid ()) {
 #else
 			if (__collate_load_error) {
 #endif