Fixed accessing out-of-bounds image coordinates while writing a black and white TIFF...

Fixed accessing out-of-bounds image coordinates while writing a black and white TIFF image.

The code assumed that the image's width is a multiple of 8, and attempted to always write per 8 pixels instead of sometimes having to write fewer pixels for the last column.

Also fixed compilo from previous commit due to not removing old code.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@68942 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775