Frame sign bias value will not be signaled in frame header. Instead,
the sign bias of reference frames are derived from their corresponding
frame offsets at both encoder and decoder.

The tool of 'frame_sign_bias' is dependent of 'frame_marker'. Compared
against baseline, the enabling of both tools obtains a small coding gain
of -0.08 ~ -0.11% in BDRate over Google lowres/midres tests.

Change-Id: I8d85dc427ced0b2152712ccf61be4be6068075b9