Build SharedExclusiveLock in Chromium.
Build SharedExclusiveLock in Chromium.

Partially un-breaks the Chromium FYI build.

TBR=jbauch@webrtc.org, tommi@webrtc.org
BUG=

Review URL: https://codereview.webrtc.org/1739713002 .

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#11765}

TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc