Fix breakage due to test_fec conversion to gtest.
Fix breakage due to test_fec conversion to gtest.

In my attempt to commit a subset of http://review.webrtc.org/1647005/
instead of all of it, I forgot to add the gtest dependency to the
test_fec.gypi. This CL fixes that.

TEST=local compile + win_rel,mac_rel,linux_rel trybots
BUG=1916
R=marpan
TBR=marpan

Review URL: https://webrtc-codereview.appspot.com/1655004

Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 04996cd5e5f49879a77c03bcbc898bc47fd1b8bb

sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc