Opus: Move complexity variable out of conditional build flag

BUG=webrtc:6708

Review-Url: https://codereview.webrtc.org/2535933002
Cr-Commit-Position: refs/heads/master@{#15277}

webrtc/modules/audio_coding/BUILD.gn

@@ -713,16 +713,16 @@ rtc_static_library("webrtc_opus") {
   ]
 
   defines = []
-
-  if (rtc_build_opus) {
-    public_deps = [
-      rtc_opus_dir,
-    ]
   if (rtc_opus_variable_complexity) {
     defines += [ "WEBRTC_OPUS_VARIABLE_COMPLEXITY=1" ]
   } else {
     defines += [ "WEBRTC_OPUS_VARIABLE_COMPLEXITY=0" ]
   }
+
+  if (rtc_build_opus) {
+    public_deps = [
+      rtc_opus_dir,
+    ]
   } else if (build_with_mozilla) {
     include_dirs = [ getenv("DIST") + "/include/opus" ]
   }