Merged r3165:3166 from branches/SDL-1.2: gcc -Wall fix in arts audio target.

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%402437

src/audio/arts/SDL_artsaudio.c

@@ -23,6 +23,11 @@
 
 /* Allow access to a raw mixing buffer */
 
+#ifdef HAVE_SIGNAL_H
+#include <signal.h>
+#endif
+#include <unistd.h>
+
 #include "SDL_timer.h"
 #include "SDL_audio.h"
 #include "../SDL_audiomem.h"