Add the condition frames_since_golden > 0 to the
early exit check for ARF usage in nonrd_pickmode.
This improves quality of first frame following ARF, where
frame_since_golden = 0.

Small/neutral gain in metrics for speed 6, neutral change in speed.

Only affects when USE_ALTREF_FOR_ONE_PASS is enabled.

Change-Id: I82e73e6ff6fc849e5ca5448563cb8a0515fe0cdc