Make unittest log printouts opt-in with a --logs flag.

TESTED=Using modules_unittests, no logs are printed by default.
Specifying --logs prints logs. gtest flags work correctly.

R=henrike@webrtc.org, kjellander@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/2181004

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@4686 4adac7df-926f-26a2-2b94-8c16560cd09d
2 files changed