dmd: build using gcc11Stdenv

The DMD test suite has been failing since we updated to gcc12, as
reported by @trofi:

  #206907 (comment)

Let's use gcc11Stdenv for now.

pkgs/top-level/all-packages.nix

@@ -6838,9 +6838,12 @@ with pkgs;
 
   dleyna-server = callPackage ../development/libraries/dleyna-server { };
 
-  dmd = callPackage ../development/compilers/dmd {
+  dmd = callPackage ../development/compilers/dmd ({
     inherit (darwin.apple_sdk.frameworks) Foundation;
-  };
+  } // lib.optionalAttrs stdenv.isLinux {
+    # https://github.com/NixOS/nixpkgs/pull/206907#issuecomment-1527034123
+    stdenv = gcc11Stdenv;
+  });
 
   dmg2img = callPackage ../tools/misc/dmg2img { };