All files without file extension are ignored by .gitignore

The workaround to ignore linux/unix binaries without file extension ignores any file without extension in the source tree.

This issue caused problems for me when trying to clean the data_sources/nmxptool for a new build. nmxptool creates some files during build which are not removed when running make clean_unix. Some of these files have no file extension (e.g. Makefile, stamp-h1, libtoo) and are therefor hidden by .gitignore when running git status or when cleaning the directory tree using git clean -fd.

Maybe ignore the Linux/Unix binaries only in the bin folder.