I am attempting to install lwgl3 as defined in https://reviews.freebsd.org/D31119. It seems I am doing something wrong in applying the .diff file to the port directory. I'm trying to follow the instructions from https://docs.freebsd.org/en/books/porters-handbook/slow-porting/#slow-patch, but am really confused on how to do this. I am very unfamiliar with using patch and .diff files, so a basic list of instructions would be helpful.