OMXCodec: Re-implement requires-flush-before-shutdown quirk

Support is already there, but is not in the codec quirk reading list.
Re-implement it as required by Broadcom's OMX

Change-Id: I1beac06af8118dcf0c248b631bc8e6dbbab2c1d5

Conflicts:
	media/libstagefright/OMXCodec.cpp