Avoid copying the comparator

Author: winner245

libcxx/include/__algorithm/min_element.h

@@ -29,7 +29,7 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 
 template <class _Comp, class _Iter, class _Sent, class _Proj>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Iter
-__min_element(_Iter __first, _Sent __last, _Comp __comp, _Proj& __proj) {
+__min_element(_Iter __first, _Sent __last, _Comp& __comp, _Proj& __proj) {
   if (__first == __last)
     return __first;