When SDL is invisible/minimized, there is no need to keep calling the
VGA refresh 33 times per second.  This patch reduces in that case the
rate to 2 times per second, which should be responsive enough for the
un-minimizing event.

(Samuel Thibault)


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4050 c046a42c-6fe2-441c-8c8c-71466251a162