Use libao driver on X11 platform

platform/x11/detect.py

@@ -111,6 +111,11 @@ def configure(env):
 	env.ParseConfig('pkg-config freetype2 --cflags --libs')
 	env.Append(CCFLAGS=['-DFREETYPE_ENABLED'])
 
+
+	if env['ao'] == 'yes':
+		env.ParseConfig('pkg-config ao --cflags --libs')
+		env.Append(CPPFLAGS=['-DAO_ENABLED'])
+
 	
 	env.Append(CPPFLAGS=['-DOPENGL_ENABLED','-DGLEW_ENABLED'])
 	env.Append(CPPFLAGS=["-DALSA_ENABLED"])

platform/x11/os_x11.cpp

@@ -1384,6 +1384,10 @@ OS_X11::OS_X11() {
 	AudioDriverManagerSW::add_driver(&driver_alsa);
 #endif
 
+#ifdef AO_ENABLED
+	AudioDriverManagerSW::add_driver(&driver_ao);
+#endif
+
 	minimized = false;
 	xim_style=NULL;
 	mouse_mode=MOUSE_MODE_VISIBLE;

platform/x11/os_x11.h

@@ -43,6 +43,7 @@
 #include "servers/spatial_sound_2d/spatial_sound_2d_server_sw.h"
 #include "drivers/rtaudio/audio_driver_rtaudio.h"
 #include "drivers/alsa/audio_driver_alsa.h"
+#include "drivers/ao/audio_driver_ao.h"
 #include "servers/physics_2d/physics_2d_server_sw.h"
 
 #include <X11/keysym.h>
@@ -129,6 +130,10 @@ class OS_X11 : public OS_Unix {
 	AudioDriverALSA driver_alsa;
 #endif
 
+#ifdef AO_ENABLED
+	AudioDriverAO driver_ao;
+#endif
+
 	enum {
 		JOYSTICKS_MAX = 8,
 		MAX_JOY_AXIS = 32768, // I've no idea