Fix typo in build_files rule.

TBR=leozwang@webrtc.org
TEST=watchlist.py

Review URL: http://webrtc-codereview.appspot.com/299011

git-svn-id: http://webrtc.googlecode.com/svn/trunk@1115 4adac7df-926f-26a2-2b94-8c16560cd09d
1 file changed