Extract third party part of g711 codec into separate target

Bug: webrtc:8366
Change-Id: I34c7ea707213e0c1a50826896da01f70c072eae5
Reviewed-on: https://webrtc-review.googlesource.com/84741
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Artem Titov <titovartem@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23724}
diff --git a/modules/audio_coding/BUILD.gn b/modules/audio_coding/BUILD.gn
index fb587c5..c3473b7 100644
--- a/modules/audio_coding/BUILD.gn
+++ b/modules/audio_coding/BUILD.gn
@@ -239,17 +239,24 @@
 rtc_source_set("g711_c") {
   poisonous = [ "audio_codecs" ]
   sources = [
-    "codecs/g711/g711.c",
-    "codecs/g711/g711.h",
     "codecs/g711/g711_interface.c",
     "codecs/g711/g711_interface.h",
   ]
   deps = [
+    ":g711_3p",
     "../..:typedefs",
     "../..:webrtc_common",
   ]
 }
 
+rtc_source_set("g711_3p") {
+  poisonous = [ "audio_codecs" ]
+  sources = [
+    "codecs/g711/g711.c",
+    "codecs/g711/g711.h",
+  ]
+}
+
 config("g722_config") {
   include_dirs = [ "codecs/g722/include" ]
 }