Merge "Add option to allow unknown warning options" am: 485127c76e am: 7394062b10

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2161661

Change-Id: Ic918cda7c06c3fee5261bbd081eedf2cd7c85efa
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

cc/config/global.go

@@ -375,6 +375,10 @@ func init() {
 			flags = append(flags, llvmNextExtraCommonGlobalCflags...)
 		}
 
+		if ctx.Config().IsEnvTrue("ALLOW_UNKNOWN_WARNING_OPTION") {
+			flags = append(flags, "-Wno-error=unknown-warning-option")
+		}
+
 		return strings.Join(flags, " ")
 	})