Fixed bug 3744 - missing SDLCALL in several functions

Ozkan Sezer

The attached patch adds missing SDLCALL to several functions, so that
they properly match the headers as intended.

test/testautomation_audio.c

@@ -46,7 +46,7 @@ int _audio_testCallbackLength;
 
 
 /* Test callback function */
-void _audio_testCallback(void *userdata, Uint8 *stream, int len)
+void SDLCALL _audio_testCallback(void *userdata, Uint8 *stream, int len)
 {
    /* track that callback was called */
    _audio_testCallbackCounter++;