Turns out my new protobuf internal entries are copied to the out dir,
so we need a new entry for that.
Tbr: mbonadei@webrtc.org
Bug: chromium:1029452
Change-Id: I5bcae3a7ff1163e051382ae741646f206ccc7324
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/171869
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#30918}