noexcept for <list>.

llvm-svn: 132562
diff --git a/libcxx/include/forward_list b/libcxx/include/forward_list
index 2387bce..aae3317 100644
--- a/libcxx/include/forward_list
+++ b/libcxx/include/forward_list
@@ -160,7 +160,7 @@
 
 template <class T, class Allocator>
     void swap(forward_list<T, Allocator>& x, forward_list<T, Allocator>& y)
-         noexcept(x.swap(y));
+         noexcept(noexcept(x.swap(y)));
 
 }  // std