Adds "msmouse" character device, which emulates a serial mouse.
Use it with -serial msmouse.

Signed-Off-By: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6559 c046a42c-6fe2-441c-8c8c-71466251a162