ndnrtc

After extensive playing with compilation options of webrtc, I finally made it (partially) compile with system's clang and using libc++. Some targets failed, but the library itself compiled and I was able to compile ndnrtc in c++11 mode against libc++.

I'm not quite sure what needs to be overridden in GYP_DEFINES, I modified directly build/common.gypi (attached) and then re-run gclient runhooks -f

I also had GYP_DEFINES="clang=1 clang_xcode=1 use_system_libcxx=1 OS=mac target_arch=x64 mac_sdk=10.9" though I'm not quite sure if any of these take any effect.