[RFC] Apply kbd layout to slave pointer with XIKeyClass

[Daniel Martin]

Hi,

when having a merged keyboard+pointer device like a Logitech Unifying
Device the keyboard layout doesn't get applied correctly.

The Xorg.log states that the InputClass (containing the XkbLayout option
etc) is choosen, `setxkbmap -query` and the _XKB_RULES_NAMES property are
fine. Though, the keyboard still uses the default US layout.
Just, executing `setxkbmap` (i.e. within the xinitrc) fixes it.

This is a cleanup of a hack I've written and attached at
    Bug 49950 - Logitech Unifying Receiver and wrong keyboard layout
    https://bugs.freedesktop.org/show_bug.cgi?id=49950,
which had been tested by Matti Nykryi and proven to work.

Though, I'm not very comfortable with the solution (patch 2 and 3)
myself and hereby ask for comments ...


Thanks in advance,
    Daniel Martin