patch 9.2.0296: Redundant and incorrect integer pointer casts in drawline.c

patch 9.2.0296: Redundant and incorrect integer pointer casts in drawline.c

Problem:  Currently `colnr_T` and `int` and the same type, so casting
          `int *` to `colnr_T *` is redundant. Additionally, even if
          they are changed to different types in the future, these casts
          are incorrect as they won't work on big-endian platforms.
Solution: Remove the casts. Also fix two cases of passing false instead
          of 0 to an integer argument (zeertzjq).

related: #19672
closes:  #19907

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>