qxl: send interrupt after migration in case ram->int_pending != 0, RHBZ #732949

qxl: send interrupt after migration in case ram->int_pending != 0, RHBZ #732949

if qxl_send_events was called from spice server context, and then
migration had completed before a call to pipe_read, the target
guest qxl driver didn't get the interrupt. In addition,
qxl_send_events ignored further interrupts of the same kind, since
ram->int_pending was set. As a result, the guest driver was stacked
or very slow (when the waiting for the interrupt was with timeout).

Signed-off-by: Yonit Halperin <yhalperi@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>