GN Templates: Move common_inherited_config to the template.

Remove common_inherited_config from the targets and add it to the
template instead.

BUG=webrtc:6187
NOTRY=True

Review-Url: https://codereview.webrtc.org/2311843002
Cr-Commit-Position: refs/heads/master@{#14069}
diff --git a/webrtc/p2p/BUILD.gn b/webrtc/p2p/BUILD.gn
index 9614896..bf9843a 100644
--- a/webrtc/p2p/BUILD.gn
+++ b/webrtc/p2p/BUILD.gn
@@ -95,10 +95,7 @@
     ]
   }
 
-  public_configs = [
-    "..:common_inherited_config",
-    ":rtc_p2p_inherited_config",
-  ]
+  public_configs = [ ":rtc_p2p_inherited_config" ]
 
   if (build_with_chromium) {
     if (is_nacl) {