time.c: fix errors on Windows and macOS; ref
`gmtime_r` detection logic was too strict.
MODIFY
mrbgems/mruby-time/src/time.c
mrbgems/mruby-time/src/time.c
@@ -66,6 +66,10 @@ double round(double x) {
#define NO_GMTIME_R
#endif
#endif
+#ifdef __STRICT_ANSI__
+/* Strict ANSI (e.g. -std=c99) do not provide gmtime_r/localtime_r */
+#define NO_GMTIME_R
+#endif
/* asctime(3) */
/* mruby usually use its own implementation of struct tm to string conversion */
@@ -125,7 +129,7 @@ gettimeofday(struct timeval *tv, void *tz)
# include <sys/time.h>
# endif
#endif
-#if !(defined(_POSIX_C_SOURCE) || defined(_BSD_SOURCE) || defined(_SVID_SOURCE))
+#ifdef NO_GMTIME_R
#define gmtime_r(t,r) gmtime(t)
#define localtime_r(t,r) localtime(t)
#endif

time.c: fix errors on Windows and macOS; ref #5354

`gmtime_r` detection logic was too strict.