Fix a compilation error with newer versions of MSVC.

Public issue https://github.com/mackron/miniaudio/issues/567

miniaudio.h

@@ -3914,7 +3914,7 @@ implications. Where supported by the compiler, alignment will be used, but other
 architecture does not require it, it will simply leave it unaligned. This is the case with old
 versions of Visual Studio, which I've confirmed with at least VC6.
 */
-#if defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 201112L)
+#if !defined(_MSC_VER) && defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 201112L)
     #include <stdalign.h>
     #define MA_ATOMIC(alignment, type)            alignas(alignment) type
 #else