lix: __structuredAttrs = true

required for separateDebugInfo

pkgs/tools/package-management/lix/common-lix.nix

···
     # We don't want the underlying GCC neither!
     stdenv.cc.cc.stdenv.cc.cc
   ];
+  __structuredAttrs = true;
 
   # We only include CMake so that Meson can locate toml11, which only ships CMake dependency metadata.
   dontUseCmakeConfigure = true;