libstagefright: Fix to free buffers properly in ERROR state

- In the ERROR state, OMXCodec::on_message tries to free the output
  buffers in the FBD sequence. This can fail if the OMX component hasn't
  been moved to idle state.
- OMXNodeInstance does not check for the return value of OMX_FreeBuffer
  call and returns the buffer entry from the list of active buffers
- This buffer ends up being unfreed which can adversely affect
  the next video playback

(cherry picked from commit 6ef3096b6db1cee7fec57da3ae4c519cdaa28bbb)

Change-Id: I9d80fd0f3c3e75da41697370f787df72316b32e4
CRs-Fixed: 329874