Rename GN public variables.

direct_dependent_configs => public_configs
Code review: https://webrtc-codereview.appspot.com/22749004/
R=fbarchard


git-svn-id: http://libyuv.googlecode.com/svn/trunk@1094 16f28f9a-4ce2-e073-06de-1de4eb20be90

BUILD.gn

@@ -69,7 +69,7 @@ source_set("libyuv") {
     "source/video_common.cc",
   ]
 
-  direct_dependent_configs = [ ":libyuv_config" ]
+  public_configs = [ ":libyuv_config" ]
 
   defines = []