Extend OpenMAX IL definitions to support AC3

OpenMAX IL does not have generic support for AC3, but IL 1.1.2 and above
supports component extension APIs, which enable us to add our own constants
and definitions.

Change-Id: Iecee4f8bb3112b0720ceae9192017e12d3fe97e3
diff --git a/include/media/openmax/OMX_IndexExt.h b/include/media/openmax/OMX_IndexExt.h
index d22df56..c47a885 100644
--- a/include/media/openmax/OMX_IndexExt.h
+++ b/include/media/openmax/OMX_IndexExt.h
@@ -57,6 +57,7 @@
 
     /* Audio parameters and configurations */
     OMX_IndexExtAudioStartUnused = OMX_IndexKhronosExtensions + 0x00400000,
+    OMX_IndexParamAudioAndroidAc3,                  /**< reference: OMX_AUDIO_PARAM_ANDROID_AC3TYPE */
 
     /* Image parameters and configurations */
     OMX_IndexExtImageStartUnused = OMX_IndexKhronosExtensions + 0x00500000,