Fix an IOC issue in vp9_rd_pick_inter_mode_sb

It is possible that the GOLDEN reference frame is not avaiable, in
which setting the predicted mv will be associated with a residual
value of INT_MAX. This commit checks this condition before
left shift and comparison with that of ALTREF frame, to avoid
overflow issue.

Change-Id: Ib98c3149dbdd016f2fe5beaafb13f67d469dd07c
1 file changed