omx_vp8dec: Component to report Role as video_decoder.vp8

This is the correct role to report, vpx is legacy and should not
be used anymore

Signed-off-by: Daniel Charles <daniel.charles@intel.com>
omx_mjpegdec: fix linking problem with OMXVideoDecodeBase

when using sandbox, libraries are open on a preload sequence and
all symbols need definition.  Once sandbox is locked, loading
libraries is not allowed.

Signed-off-by: Daniel Charles <daniel.charles@intel.com>
1.add __USE_LIBYAMI__
2.add libyami_encoder for avc encoder