Add mmsystem.h and mmreg.h for dsound.

RtAudio.cpp

@@ -5195,6 +5195,8 @@ Exit:
 // Various revisions for RtAudio 4.0 by Gary Scavone, April 2007
 // Changed device query structure for RtAudio 4.0.7, January 2010
 
+#include <mmsystem.h>
+#include <mmreg.h>
 #include <dsound.h>
 #include <assert.h>
 #include <algorithm>