Fix virtual modifiers mask extraction The calculations were performed incorrectly in several places, specifically shifting by 16 instead of 8 (= XkbNumModifiers) and masking with 0xff instead of 0xffff. More stuff that probably never worked as intended. This also makes these more grep-able when we remove the vmods/real_mods separation. Signed-off-by: Ran Benita <ran234@gmail.com>