Add a gyp target for producing a voice engine merged library.

This is based on webrtc/build/merge_libs.gyp, with a dependency on
voice_engine.gyp instead and suitable name changes.

Executing:
$ rm -rf out/
$ ./webrtc/build/gyp_webrtc -Denable_video=0 -Denable_protobuf=0
-Drelease_optimize=s webrtc/build/merge_libs_voice.gyp
$ ninja -C out/Release merged_lib_voice

results in a minimially sized voice engine lib at:
out/Release/librtc_voice_merged.a

Linux: 6.4 MB
Mac: 3.7 MB

R=braveyao@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/23659004

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@7199 4adac7df-926f-26a2-2b94-8c16560cd09d
2 files changed