Expose less targets in webrtc/rtc_tools in Chromium builds.

This should solve recent linking problems with frame_editor and also speed
up the Chromium build a little.

BUG=None
NOTRY=True

Review-Url: https://codereview.webrtc.org/3006093002
Cr-Original-Commit-Position: refs/heads/master@{#19677}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 6af0cbf4b02da1faf01011da81d97e1e0593b2ca
1 file changed