Add no_skip_block4x4_search flag in SPLITMV mode

Add a flag to always enable block4x4 search for speed=0 (good
quality) to guarantee no quality loss for speed0.

Change-Id: Ie04bbc25f7e6a33a7bfa30e05775d33148731c81
diff --git a/vp8/encoder/onyx_int.h b/vp8/encoder/onyx_int.h
index 05e8c4e..6bffd98 100644
--- a/vp8/encoder/onyx_int.h
+++ b/vp8/encoder/onyx_int.h
@@ -183,6 +183,7 @@
     int optimize_coefficients;
 
     int use_fastquant_for_pick;
+    int no_skip_block4x4_search;
 
 } SPEED_FEATURES;