vmod: take xkb_mod_set instead of the entire keymap This is the only place where the modifier information is modified. We will make it local to a given XKB file (after which it will be merged into the keymap). Currently it changes the keymap directly, which sidesteps the abstraction and leaves side-effects even if the XkbFile's compilation fails. Signed-off-by: Ran Benita <ran234@gmail.com>