Window updating is broken in SDL frontend with network type not set to auto about freerdp

[caseif]

As a note, I'm actually experiencing the same behavior when passing the +multimon flag even with the network type set to auto, and it seems to be caused by the same commit. I haven't done any digging for the root cause of this, but I feel that it may point to a more general bug in how the SDL frontend is drawing the screen.

[akallabeth]

@caseif already fixed.
was an ordering issue (SDL updates the screen between EndPaint and BeginPaint and waits in BeginPaint for everything ready
but before BeginPaint the damage rectangle was reset, so if the SDL process was late it processed an empty region.

[caseif]

Thanks for the quick fix on this!