Add Windows Clang trybots to the default set.
Add Windows Clang trybots to the default set.

BUG=chromium:568952
NOTRY=True

Review URL: https://codereview.webrtc.org/1528303002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#11063}

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