Don't declare and define gmtime()-mutex on Windows platforms
diff --git a/library/threading.c b/library/threading.c
index 8c1e25c..7c90c7c 100644
--- a/library/threading.c
+++ b/library/threading.c
@@ -56,7 +56,11 @@
  * threading.h. However, this macro is not part of the Mbed TLS public API, so
  * we keep it private by only defining it in this file
  */
+
+#if ! ( defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) )
 #define THREADING_USE_GMTIME
+#endif /* ! ( defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) ) */
+
 #endif /* !( ( defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L ) ||     \
              ( defined(_POSIX_THREAD_SAFE_FUNCTIONS ) &&                     \
                 _POSIX_THREAD_SAFE_FUNCTIONS >= 20112L ) ) */