Stagefright: Return error if codec takes too long to return a buffer.

There are many scenarios where the codec may not return a valid buffer.
In such a case, the OMXCodec::read() call hangs indefitely. Therefore,
wait() call is replaced with waitRelative() so that it timesout after a
few seconds and we exit gracefully.

Change-Id: Ie03c5d1e979b71f6253efcaa0665aa5e541cebe2
Signed-off-by: Anu Sundararajan <sanuradha@ti.com>