Move the sample conversion routines to a separate file

CMakeLists.txt

@@ -515,6 +515,7 @@ SET(OPENAL_OBJS  OpenAL32/alAuxEffectSlot.c
                  OpenAL32/alSource.c
                  OpenAL32/alState.c
                  OpenAL32/alThunk.c
+                 OpenAL32/sample_cvt.c
 )
 SET(ALC_OBJS  Alc/ALc.c
               Alc/ALu.c

OpenAL32/Include/sample_cvt.h

@@ -0,0 +1,9 @@
+#ifndef SAMPLE_CVT_H
+#define SAMPLE_CVT_H
+
+#include "AL/al.h"
+#include "alBuffer.h"
+
+void ConvertData(ALvoid *dst, enum UserFmtType dstType, const ALvoid *src, enum UserFmtType srcType, ALsizei numchans, ALsizei len, ALsizei align);
+
+#endif /* SAMPLE_CVT_H */