Disable neighbor warping for gm + obmc

Adds an option to disable warp when obmc is used with a
global motion neighbor.

Change in BDRATE on cam_lowres
gm + obmc enabled: 0.035%
gm + obmc + wm enabled: -0.005%

Change-Id: I1d6de75c7ead325cec31ed3748b5532f3658d8a7
2 files changed