Add C wrapper to access APM functions

BUG=chromium:710465
TEST=Apply whole patch series. emerge-eve webrtc-apm and
check libwebrtc_apm.so is built.

Change-Id: If26bd17ca509f83fd978890305594fdce94bfaeb
Reviewed-on: https://chromium-review.googlesource.com/970198
Commit-Ready: Hsinyu Chao <hychao@chromium.org>
Tested-by: Hsinyu Chao <hychao@chromium.org>
Reviewed-by: Cheng-Yi Chiang <cychiang@chromium.org>
2 files changed