Add logging host lookups made by TurnPort to the RtcEventLog.

The following fields are logged:
- error, if there was an error.
- elapsed time in milliseconds

BUG=webrtc:8100

Review-Url: https://codereview.webrtc.org/2996933003
Cr-Original-Commit-Position: refs/heads/master@{#19574}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: c251cb13c08aba710ba3a12588beb4aa172c7323
25 files changed