Refactor and fix do_sendkey (Jan Kiszka).

Looking at the sendkey implementation, planning to enhance it with a
hold time argument, I found some potential out-of-bound access and not
very readable code. Here is a fix for the former and a (subjective)
improvement of the latter.

Signed-off-by: Jan Kiszka <jan.kiszka@web.de>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4657 c046a42c-6fe2-441c-8c8c-71466251a162
