vl: change QEMU state machine for system reset

vl: change QEMU state machine for system reset

This patch implements proposal from Paolo to handle system reset when
the guest is not running.

"After a reset, main_loop_should_exit should actually transition
to VM_STATE_PRELAUNCH (*not* RUN_STATE_PAUSED) for *all* states except
RUN_STATE_INMIGRATE, RUN_STATE_SAVE_VM (which I think cannot happen
there) and (of course) RUN_STATE_RUNNING."

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1455369986-20353-1-git-send-email-den@openvz.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>