libstdc++: Remove extraneous &&

libstdc++-v3/ChangeLog

 2020-02-07  Patrick Palka  <ppalka@redhat.com>
 
+	* include/bits/ranges_algo.h: Remove extraneous &&.
+
 	* include/std/ranges (ranges::__detail::__stream_extractable,
 	ranges::basic_istream_view, ranges::istream_view): Define.
 	* testsuite/std/ranges/istream_view: New test.

libstdc++-v3/include/bits/ranges_algo.h

@@ -1250,7 +1250,7 @@ namespace ranges
       [[no_unique_address]] _Out  out;
 
       template<typename _IIter1, typename _IIter2, typename _OOut>
-	requires convertible_to<const _Iter1&, _IIter1> &&
+	requires convertible_to<const _Iter1&, _IIter1>
 	  && convertible_to<const _Iter2&, _IIter2>
 	  && convertible_to<const _Out&, _OOut>
 	operator binary_transform_result<_IIter1, _IIter2, _OOut>() const &