Added a rt speed 12

We target this speed to achieve similar encoding speed and better
compression than vp8 rt mode with cpu-used at -12.

Change-Id: Ic1bb4371c81a17ea80e83459c1cbf4c09a3498e8

vp9/encoder/vp9_speed_features.c

diff --git a/vp9/encoder/vp9_speed_features.c b/vp9/encoder/vp9_speed_features.c
index 450cab4..dc9bdeb 100644
--- a/vp9/encoder/vp9_speed_features.c
+++ b/vp9/encoder/vp9_speed_features.c
@@ -294,7 +294,11 @@
         800 : 300;
     sf->elevate_newmv_thresh = 2500;
   }
-  if (speed >= 8) {
+  if (speed >= 12) {
+    sf->elevate_newmv_thresh = 4000;
+    sf->mv.subpel_force_stop = 2;
+  }
+  if (speed >= 13) {
     int i;
     sf->max_intra_bsize = BLOCK_32X32;
     for (i = 0; i < BLOCK_SIZES; ++i)