mingw: use gcc-like memory barrier

Edward Thomson · Edward Thomson · commit 6e0fc1a63138 · 2016-02-08T16:30:41.000-08:00
Use the gcc-like memory barrier (__sync_synchronize) on mingw.
diff --git a/src/thread-utils.h b/src/thread-utils.h
@@ -275,7 +275,7 @@ GIT_INLINE(int) git_atomic_get(git_atomic *a)
 
 extern int git_online_cpus(void);
 
-#if defined(GIT_THREADS) && defined(GIT_WIN32)
+#if defined(GIT_THREADS) && defined(_MSC_VER)
 # define GIT_MEMORY_BARRIER MemoryBarrier()
 #elif defined(GIT_THREADS)
 # define GIT_MEMORY_BARRIER __sync_synchronize()
