xkbcomp: Do not discard extra bits in vmod masks Since we accept numeric values for the vmod mask in the keymap, we may have extra bits set that encode *no* real/virtual modifier. Keep them unchanged for consistency. E.g. the following keymap: xkb_keymap { xkb_keycodes { <a> = 38; }; xkb_symbols { virtual_modifiers X = 0xf0000000; key <a> { [ SetMods(mods = 0x00001100) ] }; }; }; would compile to: xkb_keymap { xkb_keycodes { <a> = 38; }; xkb_symbols { virtual_modifiers X = 0xf0000000; // Internal state key <a> { [ SetMods(mods = 0xf0001000) ] }; // Serialization key <a> { [ SetMods(mods = 0x00001100) ] }; }; };