Don't select audio codecs depending on GN vars `build_with_{chromium|mozilla}`

BUG=webrtc:8343

Change-Id: I5943006a4da17f72eb88eae9d7ea57574d54f680
Reviewed-on: https://webrtc-review.googlesource.com/9401
Commit-Queue: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Oskar Sundbom <ossu@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20540}
diff --git a/webrtc.gni b/webrtc.gni
index 7154b87..a4b7c18 100644
--- a/webrtc.gni
+++ b/webrtc.gni
@@ -33,6 +33,9 @@
 }
 
 declare_args() {
+  # Include the iLBC audio codec?
+  rtc_include_ilbc = true
+
   # Disable this to avoid building the Opus audio codec.
   rtc_include_opus = true
 
@@ -173,9 +176,6 @@
 # depend on the possibly overridden variables in the first
 # declare_args block.
 declare_args() {
-  # Include the iLBC audio codec?
-  rtc_include_ilbc = !(build_with_chromium || build_with_mozilla)
-
   rtc_restrict_logging = build_with_chromium
 
   # Excluded in Chromium since its prerequisites don't require Pulse Audio.