MPS: face-cache

[Gerd Möllmann]

FYI: Just found this while randomly debugging

  static uintptr_t
  lface_hash (Lisp_Object *v)
  {
    return (hash_string_case_insensitive (v[LFACE_FAMILY_INDEX])
            ^ hash_string_case_insensitive (v[LFACE_FOUNDRY_INDEX])
            ^ hash_string_case_insensitive (v[LFACE_FOREGROUND_INDEX])
            ^ hash_string_case_insensitive (v[LFACE_BACKGROUND_INDEX])
            ^ XHASH (v[LFACE_WEIGHT_INDEX])
            ^ XHASH (v[LFACE_SLANT_INDEX])
            ^ XHASH (v[LFACE_SWIDTH_INDEX])
            ^ XHASH (v[LFACE_HEIGHT_INDEX]));
  }

XHASH is address dependent, so it can't work. That should be igc_hash
for MPS.

Not today, though. Good night!