vp9: 1 pass vbr: Reduce base qp for active_best_quality for inter-frames.

Reduce factor for setting base-qp for active_best_quality (for inter-frames).
Small increase in metrics on yt live set.

Change-Id: I9cf0ac797783aeddbfaf1ff510696c9035d7c5ee

vp9/encoder/vp9_ratectrl.c

diff --git a/vp9/encoder/vp9_ratectrl.c b/vp9/encoder/vp9_ratectrl.c
index b2d748e..1e6c152 100644
--- a/vp9/encoder/vp9_ratectrl.c
+++ b/vp9/encoder/vp9_ratectrl.c
@@ -956,7 +956,7 @@
       // Use the min of the average Q (with some increase) and
       // active_worst_quality as basis for active_best.
       if (cm->current_video_frame > 1) {
-        q = VPXMIN(((35 * rc->avg_frame_qindex[INTER_FRAME]) >> 5),
+        q = VPXMIN(((17 * rc->avg_frame_qindex[INTER_FRAME]) >> 4),
                     active_worst_quality);
         active_best_quality = inter_minq[q];
       } else {