Force better lower quantizer keyframe in case of high quantizer.

Change-Id: Ie69a164bc166b6a8819777038d65a7d9f9c3361f

vp9/encoder/vp9_ratectrl.c

diff --git a/vp9/encoder/vp9_ratectrl.c b/vp9/encoder/vp9_ratectrl.c
index 9b6c773..724a2c3 100644
--- a/vp9/encoder/vp9_ratectrl.c
+++ b/vp9/encoder/vp9_ratectrl.c
@@ -559,7 +559,7 @@
   int adjustment = 0;
   int active_worst_quality;
   if (cm->frame_type == KEY_FRAME)
-    return rc->worst_quality;
+    return rc->worst_quality * 4 / 5;
   if (cm->current_video_frame > 1)
     active_worst_quality = MIN(rc->worst_quality,
                                rc->avg_frame_qindex[INTER_FRAME] * 5 / 4);