state: apply control transformation on utf8/utf32 keysym strings

This is required by the specification:
http://www.x.org/releases/current/doc/kbproto/xkbproto.html#Interpreting_the_Control_Modifier
and clients expect this to happen.

https://bugs.freedesktop.org/show_bug.cgi?id=75892

Reported-by: Gatis Paeglis <gatis.paeglis@digia.com>
Signed-off-by: Ran Benita <ran234@gmail.com>