Add exports to allow libyuv to be built as a shared lib.
BUG=99
TEST=shared lib builds without impact and unittests link against import lib.
Review URL: https://webrtc-codereview.appspot.com/844005

git-svn-id: http://libyuv.googlecode.com/svn/trunk@379 16f28f9a-4ce2-e073-06de-1de4eb20be90
diff --git a/source/rotate_argb.cc b/source/rotate_argb.cc
index 277b6cb..33e1050 100644
--- a/source/rotate_argb.cc
+++ b/source/rotate_argb.cc
@@ -126,6 +126,7 @@
   }
 }
 
+LIBYUV_API
 int ARGBRotate(const uint8* src_argb, int src_stride_argb,
                uint8* dst_argb, int dst_stride_argb,
                int width, int height,