DataChannel-only libwebrtc

Equivalently, https://github.com/keroserene/go-webrtc/issues/10

This is my first working patch, https://gist.github.com/arlolra/f43b3e980e88a534b61c7a5ef3903124

It applies against f33698296719f956497d2dbff81b5080864a8804, which was HEAD of branch-heads/52 when I started, and the current build of go-webrtc (see https://github.com/keroserene/go-webrtc/pull/42)

To use it,

gclient sync -r f33698296719f956497d2dbff81b5080864a8804
cd src/
git am the.patch
GYP_DEFINES="include_tests=0 include_examples=0" python webrtc/build/gyp_webrtc webrtc/api/api.gyp
ninja -C out/Release

Then do the usual concatenating stuff. It's important to note here that the patch ifdefs in a few headers, so be sure to update those or you'll get some segfaults.

All the go-webrtc / snowflake tests passed, and I was able to bootstrap a tor client with it.

I was also able to make this change to go-webrtc/webrtc-darwin-amd64.pc,

-       -framework AppKit \
-       -framework CoreAudio \
-       -framework AudioToolbox
+       -framework AppKit

This trimmed the build by about 10MB, and I assume with a little more work can be improved.