Update for compiling WASAPI on both MinGW and VS.

RtAudio.h

@@ -568,6 +568,10 @@ class RtAudio
 
 // Operating system dependent thread functionality.
 #if defined(__WINDOWS_DS__) || defined(__WINDOWS_ASIO__) || defined(__WINDOWS_WASAPI__)
+
+  #ifndef NOMINMAX
+    #define NOMINMAX
+  #endif
   #include <windows.h>
   #include <process.h>