Add -audio-test-out option to the core.

This option can be used to quickly check audio output (without
having to boot a full AVD and launch a sound-playing application).

Usage:
   emulator <other-options> -qemu -audio-test-out
   qemu-android <other-options> -audio-test-out

This simply generates an ugly saw signal, but that's enough for us.

Change-Id: I060300b4000b9705d181c6262de8d4d13c749e69
diff --git a/vl-android.c b/vl-android.c
index 57be79c..3fb50ea 100644
--- a/vl-android.c
+++ b/vl-android.c
@@ -191,6 +191,7 @@
 #include "android/hw-lcd.h"
 #include "android/boot-properties.h"
 #include "android/core-init-utils.h"
+#include "android/audio-test.h"
 
 #ifdef CONFIG_STANDALONE_CORE
 /* Verbose value used by the standalone emulator core (without UI) */
@@ -4641,6 +4642,10 @@
                 android_op_ui_settings = (char*)optarg;
                 break;
 
+            case QEMU_OPTION_audio_test_out:
+                android_audio_test_start_out();
+                break;
+
 #ifdef CONFIG_MEMCHECK
             case QEMU_OPTION_android_memcheck:
                 android_op_memcheck = (char*)optarg;