GN: Fix windows clang errors. Attempt 2.

webrtc/modules/audio_coding/BUILD.gn

Index: webrtc/modules/audio_coding/BUILD.gn
diff --git a/webrtc/modules/audio_coding/BUILD.gn b/webrtc/modules/audio_coding/BUILD.gn
index 0ea5035bdd099a79687074626b4bc74046e9df80..89183476498cd25169e2f0134bc8b4c78a7793b7 100644
--- a/webrtc/modules/audio_coding/BUILD.gn
+++ b/webrtc/modules/audio_coding/BUILD.gn
@@ -1537,6 +1537,16 @@ if (rtc_include_tests) {
     }
   }
 
+  config("isac_test_warnings_config") {
+    if (is_win && is_clang) {
+      cflags = [
+        # Disable warnings failing when compiling with Clang on Windows.
+        # https://bugs.chromium.org/p/webrtc/issues/detail?id=5366
+        "-Wno-format",
+      ]
+    }
+  }
+
   executable("isac_test") {
     testonly = true
 
@@ -1557,13 +1567,7 @@ if (rtc_include_tests) {
       "//build/config/sanitizers:deps",
     ]
 
-    if (is_win && is_clang) {
-      cflags = [
-        # Disable warnings failing when compiling with Clang on Windows.
-        # https://bugs.chromium.org/p/webrtc/issues/detail?id=5366
-        "-Wno-format",
-      ]
-    }
+    configs += [ ":isac_test_warnings_config" ]
   }
 
   executable("g711_test") {