Remove last mention of ortc from the codebase.

TBR=kwiberg@webrtc.org

No-Try: True
Bug: webrtc:9824
Change-Id: I28af4b45a69b39cdc80ea4b21fef3716ded62a72
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/138269
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28067}
diff --git a/.gn b/.gn
index 5c9f362..3ff65c1 100644
--- a/.gn
+++ b/.gn
@@ -32,7 +32,6 @@
   "//logging/*",
   "//media/*",
   "//modules/*",
-  "//ortc/*",
   "//p2p/*",
   "//pc/*",
   "//rtc_base/*",