Revert "osm2xmap: mark as broken"

This reverts commit a57e9fc6c0.
After the parent commit it builds again.  For now; future seems bleak.

pkgs/applications/misc/osm2xmap/default.nix

@@ -29,7 +29,5 @@ stdenv.mkDerivation rec {
     license = licenses.gpl3;
     maintainers = [ maintainers.mpickering ];
     platforms = with lib.platforms; linux;
-    # it probably needs https://proj.org/development/migration.html
-    broken = true;
   };
 }