Add libjingle_peerconnection_unittest to GN targets.
Add libjingle_peerconnection_unittest to GN targets.

BUG=webrtc:6037
NOTRY=True

Review-Url: https://codereview.webrtc.org/2226093003
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#13703}

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