Broke out 'level_indicator' of the voice_engine GN target. This is
needed for the new audio_mixer to depend on just
'voice_engine:level_indicator' instead of the whole voice_engine and
avoid a circular dependency.

TBR=henrika@webrtc.org

NOTRY=True

Review-Url: https://codereview.webrtc.org/2221103004
Cr-Commit-Position: refs/heads/master@{#13709}
diff --git a/.gn b/.gn
index 460eae6..e151f7c 100644
--- a/.gn
+++ b/.gn
@@ -19,7 +19,7 @@
 # their includes checked for proper dependencies when you run either
 # "gn check" or "gn gen --check".
 # TODO(kjellander): Keep adding paths to this list as work in webrtc:5589 is done.
-check_targets = []
+check_targets = [ "//webrtc/voice_engine:level_indicator" ]
 
 # These are the list of GN files that run exec_script. This whitelist exists
 # to force additional review for new uses of exec_script, which is strongly
@@ -49,4 +49,5 @@
   "//third_party/openh264/BUILD.gn",
   "//third_party/opus/BUILD.gn",
   "//webrtc/modules/video_render/BUILD.gn",
+  "//webrtc/modules/video_render/BUILD.gn",
 ]