Build webrtc_nonparallel_tests under GN.

BUG=webrtc:5949, webrtc:6040
R=danilchap@webrtc.org
TBR=kjellander@webrtc.org

Review URL: https://codereview.webrtc.org/2100173002 .

Cr-Original-Commit-Position: refs/heads/master@{#13299}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: ac968bdab6e0b95072266aa09de2afb15c82ce1b
1 file changed