When pel panning is active, one more byte is read from each of the VGA
memory planes. This has to be accounted in the computation of region_end,
otherwise vga_draw_graphic() fails an assertion:
qemu-system-i386: ../system/physmem.c:946: cpu_physical_memory_snapshot_get_dirty: Assertion `start + length <= snap->end' failed.
Reported-by: Helge Konetzka <hk@zapateado.de>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2244
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
3b6d2b1962