Update .gitignore
Update .gitignore

This should have been done in https://codereview.webrtc.org/1503883002

TBR=phoglund@webrtc.org
BUG=

Review URL: https://codereview.webrtc.org/1575113003 .

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#11217}

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