This patch only includes inter frame reconstruction using gm
parameters when GLOBAL_MOTION and/or VP9_HIGHBITDEPTH are enabled.
GM is not currently used when EXT_INTER or DUAL_FILTER is enabled.
This will be added in a followup patch. For now, these experiments
will take precedence over GLOBAL_MOTION when they are all enabled.

Change-Id: I930ddda529c44d7245dbb56db3c9c5524cf45473