[cflags] Allow set but unused parameter in third party code

Bug: 77973
Change-Id: I8a77cc1a31468f0d15eca330a9330680741db746
diff --git a/BUILD.gn b/BUILD.gn
index 19ab857..3e20e7b 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -372,5 +372,6 @@
   }
 
   configs += [ "//build/config:Wno-conversion" ]
+  configs += [ "//build/config:Wno-unused-but-set-parameter" ]
 }