Add libjingle_peerconnection_objc_test to buildbot_tests.py
Add libjingle_peerconnection_objc_test to buildbot_tests.py

To run this test, the executable in
libjingle_peerconnection_objc_test.app/Contents/MacOS/libjingle_peerconnection_objc_test
must be run. Running executables like this is not supported by
the buildbot scripts, which makes the paths to the stdio invalid.
Adding it to our command-line wrapping script and executing it as
'libjingle_peerconnection_objc_test' on the bots should work around
this limitation.

BUG=2120
TEST=locally building and executing the test on Mac using:
GYP_DEFINES="host_arch=x64 target_arch=x64" gclient runhooks
ninja -C out/Release
out/Release/buildbot_tests.py -t libjingle_peerconnection_objc_test

R=phoglund@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/2275007

Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: ebd3ab0ce1b1f5b031f648f98a5865446416ef4e

sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc