A pointer to the data of one qimage is used, with an offset, in a copy.
In the mono case, that could lead to overflow: the last row would
of the copy would stretch 1 byte beyond the end of the allocated
area. Fix by reducing the height of the copy, so that it keeps
within the allocated memory.
Task-number: QTBUG-28322
Change-Id: I09abfc83f738f8af000fc50f8c94f63dba3a6cfe
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>
a3a4114f53