The compile completed to the end without issue.
As suggested by R. Belmont, opening the file src/osd/sdl/sdl.mak in a text editor and finding this line:
# SDL_LIBVER = sdl2
Removing the # so it simply reads
SDL_LIBVER = sdl2
and then saving did the trick.
Installed SDL2 and commented out the line as per above..
Did "make clean" followed by "make". This is what did the trick. Just in case, I also entered "./endings" before the make commands. Everything else on http://forums.bannister.org/ubbthreads.php?ubb=showflat&Number=58897&page=1
remains the same with this one exception. So be sure to follow the URL in the previous sentence and after you complete all
of STEP 2 simply follow the above comment removal steps and you should be good to go.
** It's noteworthy to understand that as of this writing the github repo include the comment fix so in no time this post will become redundant.
A huge and special thank you to R. Belmont for assisting me throughout the process.