Add a tool to fix (some) errors reported by gn gen --check.
Add a tool to fix (some) errors reported by gn gen --check.

BUG=webrtc:6828
R=kjellander@webrtc.org
NOTRY=True

Review-Url: https://codereview.webrtc.org/2555813003
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#15483}

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