lib/systems: ensure native `emulator` is a string (#358507)

          # to an emulator program. That is, if an emulator requires additional

          # arguments, a wrapper should be used.

          if pkgs.stdenv.hostPlatform.canExecute final

          then pkgs.writeShellScript "exec" ''exec "$@"''

          then lib.getExe (pkgs.writeShellScriptBin "exec" ''exec "$@"'')

          else if final.isWindows

          then "${wine}/bin/wine${optionalString (final.parsed.cpu.bits == 64) "64"}"

          else if final.isLinux && pkgs.stdenv.hostPlatform.isLinux && final.qemuArch != null