Don't neglect to "return *this".


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@165860 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/functional b/include/functional
index 8c166b7..ec5c5e5 100644
--- a/include/functional
+++ b/include/functional
@@ -1351,6 +1351,7 @@
         __f_ = __f.__f_;
         __f.__f_ = 0;
     }
+    return *this;
 }
 
 template<class _Rp, class ..._ArgTypes>
@@ -1362,6 +1363,7 @@
     else if (__f_)
         __f_->destroy_deallocate();
     __f_ = 0;
+    return *this;
 }
 
 template<class _Rp, class ..._ArgTypes>