Fix XBM files on NS (bug#26133)

Fix XBM files on NS (bug#26133)

Reinstate some of the functionality removed in commit
67a878f78f879ce534232408c34dd11f42dd802b.

* src/nsimage.m (ns_image_from_XBM): Use new reverseBytes argument.
([EmacsImage initFromXBM:width:height:fg:bg:reverseBytes:]): Add
ability to reverse the contents of each byte for use with XBMs, while
still working with fringe bitmaps.
* src/nsterm.h
([EmacsImage initFromXBM:width:height:fg:bg:reverseBytes:]): Modified
function definition.
* src/nsterm.m (ns_draw_fringe_bitmap): Use new reverseBytes argument.