Update phonertc submodule with webrtc libs and local video mirroring

commit fee1e01553791319b34d8a92a321076d1fdcd151
Author: Joseph Frazier <joseph@onsip.com>
Date:   Wed Aug 6 21:35:00 2014 -0400

    (Android) Mirror local video when rendering

    See 6f44a0040fc04bca31a685dbb9d67939f190c129

commit ad982e927ee2df09e17ed6ef98e5cfd7774ce6ca
Author: Joseph Frazier <joseph@onsip.com>
Date:   Wed Aug 6 20:32:10 2014 -0400

    Update Android WebRTC libraries to r6783

    There were newer revisions available at the time of this commit, but they would
    not build (see https://code.google.com/p/webrtc/issues/detail?id=3622#c12)