Fix presubmit check for webrtc/base.
Fix presubmit check for webrtc/base.

Show a warning only when there's something to warn about.

TBR=kjellander@webrtc.org
NOTRY=True
BUG=webrtc:7634

Review-Url: https://codereview.webrtc.org/2974093002
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#18952}

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