.gitignore: remove inappropriate content
The root .gitignore contains Makefile in lines 334 and 340. This is inappropriate, since Makefile in DENISE commonly is not a derived file, but original source code under version control. When importing vendor drops this way Makefiles will be missing, if 'git add' is not issued with the '--force' option.
Apparently the file .gitignore was copied from a project with makes use of cmake. In such environments Makefile is a secondary file which indeed should not be under version control. I recommend to remove all entries from .gitignore which are not actually required by DENISE.