Bug 1406736 Match MinGW's macro so we declare gmtime_r under MinGW too r=froydnj

MozReview-Commit-ID: 2U2ToeyVUUt

--HG--
extra : rebase_source : a4ebd43f4529cc6b815f5bb849021a994dda959f

security/pkix/test/lib/pkixtestutil.cpp

@@ -251,7 +251,7 @@ Integer(long value)
 enum TimeEncoding { UTCTime = 0, GeneralizedTime = 1 };
 
 // Windows doesn't provide gmtime_r, but it provides something very similar.
-#if defined(WIN32) && !defined(_POSIX_THREAD_SAFE_FUNCTIONS)
+#if defined(WIN32) && (!defined(_POSIX_C_SOURCE) || !defined(_POSIX_THREAD_SAFE_FUNCTIONS))
 static tm*
 gmtime_r(const time_t* t, /*out*/ tm* exploded)
 {