VP9 denoiser bug-fix: artifact caused by false buffer swap.

The artifact occurs periodically when VP9 denoiser is on and
refresh_golden_frame happen. When refresh_golden_frame happen,
we should copy the frame buffer instead of swapping the pointers.

Change-Id: Ib3204c4b04db28ecf439c6d9e61f3d146f04196d
1 file changed