Add test for scaling color accuracy

BUG=401
TESTED=scale_color test

Review URL: https://webrtc-codereview.appspot.com/39099004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@1417 16f28f9a-4ce2-e073-06de-1de4eb20be90

CMakeLists.txt

@@ -59,6 +59,7 @@ set(ly_unittest_sources
   ${ly_base_dir}/unit_test/rotate_argb_test.cc
   ${ly_base_dir}/unit_test/rotate_test.cc
   ${ly_base_dir}/unit_test/scale_argb_test.cc
+  ${ly_base_dir}/unit_test/scale_color_test.cc
   ${ly_base_dir}/unit_test/scale_test.cc
   ${ly_base_dir}/unit_test/unit_test.cc
   ${ly_base_dir}/unit_test/video_common_test.cc

libyuv_test.gyp

@@ -44,6 +44,7 @@
         'unit_test/rotate_argb_test.cc',
         'unit_test/rotate_test.cc',
         'unit_test/scale_argb_test.cc',
+        'unit_test/scale_color_test.cc',
         'unit_test/scale_test.cc',
         'unit_test/unit_test.cc',
         'unit_test/video_common_test.cc',