Fix path to perf Python scripts in test.gyp

The path in test.gyp in r3411 was incorrect since it was based on the symlink that does not exist on Windows.
This CL changes it to reference the actual path in /tools/perf

TBR=phoglund
BUG=none
TEST=win try bot.

Review URL: https://webrtc-codereview.appspot.com/1074006

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@3413 4adac7df-926f-26a2-2b94-8c16560cd09d
1 file changed