[PATCH] libstdc++: Add feature test macros for std::ranges::shift_left and std::ranges::shift_right in std.cc.in

[hexne]

Previously, std::ranges::shift_left and std::ranges::shift_right did
not use feature test macros, so compiling std.cc files under c++20
would result in compilation failure

Tested on x86_64-linux.

Signed-off-by: hexne <printfne@gmail.com>

diff --git a/libstdc++-v3/src/c++23/std.cc.in b/libstdc++-v3/src/c++23/std.cc.in
index 9301ed90c00..1c2346b9f63 100644
--- a/libstdc++-v3/src/c++23/std.cc.in
+++ b/libstdc++-v3/src/c++23/std.cc.in
@@ -277,15 +277,14 @@ export namespace std
     using std::ranges::shuffle;
   }
   using std::shift_left;
-  namespace ranges
-  {
-    using std::ranges::shift_left;
-  }
   using std::shift_right;
+#if __cpp_lib_shift >= 202202L
   namespace ranges
   {
+    using std::ranges::shift_left;
     using std::ranges::shift_right;
   }
+#endif
   using std::sort;
   namespace ranges
   {