Cygwin: convert localtime_wrapper.c to plain C source

That also requires a small tweak to localtime.c.patch, otherwise
GCC complains about the position of the 'trydefrules' label.
Also, simplify includes.

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

winsup/cygwin/Makefile.in

@@ -561,7 +561,7 @@ TARGET_LIBS:=$(LIB_NAME) $(CYGWIN_START) $(GMON_START) $(LIBGMON_A) $(SUBLIBS) $
 
 ifneq "${filter -O%,$(CFLAGS)}" ""
 dtable_CFLAGS:=-fcheck-new
-localtime_CFLAGS:=-fwrapv -fpermissive
+localtime_CFLAGS:=-fwrapv
 malloc_CFLAGS:=-O3
 sync_CFLAGS:=-O3
 ifeq ($(target_cpu),i686)
@@ -737,7 +737,7 @@ shared.o: shared_info_magic.h
 localtime.o: $(srcdir)/tzcode/localtime_wrapper.c $(srcdir)/tzcode/localtime.c.patch
 	(cd $(srcdir)/tzcode && \
 		patch -u -o localtime.c.patched localtime.c localtime.c.patch)
-	$(CXX) ${CXXFLAGS} ${localtime_CFLAGS} \
+	$(CC) ${COMMON_CFLAGS} ${localtime_CFLAGS} \
 		-I$(target_builddir)/winsup/cygwin \
 		-I$(srcdir) -I$(srcdir)/tzcode -c -o $@ $<
 

winsup/cygwin/tzcode/localtime.c.patch

@@ -32,13 +32,15 @@
  	nread = read(fid, up->buf, sizeof up->buf);
  	if (nread < (ssize_t)tzheadsize) {
  		int err = nread < 0 ? errno : EINVAL;
-@@ -501,6 +501,15 @@
+@@ -501,6 +501,17 @@
  	}
  	if (close(fid) < 0)
  		return errno;
 +	if (0) {
++		const char *base;
 +trydefrules:
-+		const char *base = strrchr(name, '/');
++
++		base = strrchr(name, '/');
 +		base = base ? base + 1 : name;
 +		if (strcmp(base, TZDEFRULES))
 +		    return errno;
@@ -48,7 +50,7 @@
  	for (stored = 4; stored <= 8; stored *= 2) {
  		int_fast32_t ttisstdcnt = detzcode(up->tzhead.tzh_ttisstdcnt);
  		int_fast32_t ttisutcnt = detzcode(up->tzhead.tzh_ttisutcnt);
-@@ -1417,6 +1426,8 @@
+@@ -1417,6 +1428,8 @@
  tzsetlcl(char const *name)
  {
  	struct state *sp = __lclptr;

winsup/cygwin/tzcode/localtime_wrapper.c

@@ -6,16 +6,17 @@ This software is a copyrighted work licensed under the terms of the
 Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
 details. */
 
-#include "../winsup.h"
-#include "../sync.h"
-#include "../include/cygwin/version.h"
+#include "winsup.h"
+#include "perprocess.h"
 #include "tz_posixrules.h"
+#include <cygwin/version.h>
+#include <stdlib.h>
 
-static NO_COPY muto tzset_guard;
+static NO_COPY SRWLOCK tzset_guard = SRWLOCK_INIT;
 
-// Convert these NetBSD rwlock ops into Cygwin muto ops
-#define rwlock_wrlock(X) tzset_guard.init("tzset_guard")->acquire()
-#define rwlock_unlock(X) tzset_guard.release()
+// Convert these NetBSD rwlock ops into SRWLocks
+#define rwlock_wrlock(X) AcquireSRWLockExclusive(&tzset_guard)
+#define rwlock_unlock(X) ReleaseSRWLockExclusive(&tzset_guard)
 
 // Set these NetBSD-related option #defines appropriately for Cygwin
 //#define STD_INSPIRED	// early-include private.h below does this
@@ -109,9 +110,6 @@ tzgetwintzi (char *wildabbr, char *outbuf)
 }
 
 // Get ready to wrap NetBSD's localtime.c
-#ifdef __cplusplus
-extern "C" {
-#endif
 
 // Pull these in early to catch any small issues before the real test
 #include "private.h"
@@ -126,19 +124,15 @@ extern "C" {
 */
 #include "localtime.c.patched"
 
-#ifdef __cplusplus
-}
-#endif
-
 // Don't forget these Cygwin-specific additions from this point to EOF
 EXPORT_ALIAS (tzset_unlocked, _tzset_unlocked)
 
-extern "C" long
+long
 __cygwin_gettzoffset (const struct tm *tmp)
 {
 #ifdef TM_GMTOFF
     if (CYGWIN_VERSION_CHECK_FOR_EXTRA_TM_MEMBERS)
-    	return tmp->TM_GMTOFF;
+	return tmp->TM_GMTOFF;
 #endif /* defined TM_GMTOFF */
     __tzinfo_type *tz = __gettzinfo ();
     /* The sign of this is exactly opposite the envvar TZ.  We
@@ -148,7 +142,7 @@ __cygwin_gettzoffset (const struct tm *tmp)
     return offset;
 }
 
-extern "C" const char *
+const char *
 __cygwin_gettzname (const struct tm *tmp)
 {
 #ifdef TM_ZONE