output/openal: support OpenAL plugin on Mac OS X

configure.ac

@@ -791,9 +791,19 @@ fi
 AM_CONDITIONAL(HAVE_OSS, test x$enable_oss = xyes)
 
 if test x$enable_openal = xyes; then
+	if test x$enable_osx = xyes; then
+		AC_CHECK_HEADERS([OpenAL/al.h OpenAL/alc.h], [], [enable_openal=no])
+		if test x$enable_openal = xyes; then
+			OPENAL_LIBS="-framework OpenAL"
+			AC_DEFINE(HAVE_OPENAL, 1, [Define for OpenAL support])
+		else
+			AC_MSG_WARN(OpenAL headers not found -- disabling OpenAL support)
+		fi
+	else
 		PKG_CHECK_MODULES([OPENAL], [openal],
 			AC_DEFINE(HAVE_OPENAL, 1, [Define for OpenAL support]),
 			enable_openal=no)
+	fi
 fi
 
 if test x$enable_openal = xyes; then

src/output/openal_plugin.c

@@ -19,11 +19,17 @@
 
 #include "../output_api.h"
 #include "../timer.h"
+#include "config.h"
 
 #include <glib.h>
 
+#ifndef HAVE_OSX
 #include <AL/al.h>
 #include <AL/alc.h>
+#else
+#include <OpenAL/al.h>
+#include <OpenAL/alc.h>
+#endif
 
 #undef G_LOG_DOMAIN
 #define G_LOG_DOMAIN "openal"