Quash a whole bunch of warnings

llvm-svn: 145624
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: c206366fd7774aff222578c2680b931a4c2c35ba
diff --git a/include/functional b/include/functional
index 1ade26f..17a36cc 100644
--- a/include/functional
+++ b/include/functional
@@ -1573,7 +1573,7 @@
     !__is_reference_wrapper<_Ti>::value,
     _Ti&
 >::type
-__mu(_Ti& __ti, _Uj& __uj)
+__mu(_Ti& __ti, _Uj&)
 {
     return __ti;
 }