Change scale 3/8 to use scratch registers for constants

BUG=none
TEST=none
Review URL: https://webrtc-codereview.appspot.com/576011

git-svn-id: http://libyuv.googlecode.com/svn/trunk@267 16f28f9a-4ce2-e073-06de-1de4eb20be90

README.chromium

 Name: libyuv
 URL: http://code.google.com/p/libyuv/
-Version: 265
+Version: 267
 License: BSD
 License File: LICENSE
 

include/libyuv/version.h

@@ -11,7 +11,7 @@
 #ifndef INCLUDE_LIBYUV_VERSION_H_
 #define INCLUDE_LIBYUV_VERSION_H_
 
-#define LIBYUV_VERSION 265
+#define LIBYUV_VERSION 267
 
 #endif  // INCLUDE_LIBYUV_VERSION_H_