libstagefright: Customize AV sync behavior

Based on the property, whenever video decoder takes more time
for decoding and causing few consecutive frame drops to maintain
the AV sync, then disable AV sync till it recovers.

This change will avoid freeze whenever any video clips out side
of the supported spec are being played though audio and video
are out of sync.
This improves user experience

Change-Id: Ia4ee899ff2515684259b88f66af216871a7bd38c