fix mingw and msvc cmake builds.

Common/OSVersion.cpp

@@ -1,6 +1,6 @@
 #include "ppsspp_config.h"
 
-#ifdef _MSC_VER
+#ifdef _WIN32
 
 #include <cstdint>
 #include "OSVersion.h"
@@ -93,4 +93,4 @@ std::string GetWindowsSystemArchitecture() {
 		return "(Unknown)";
 }
 
-#endif
+#endif