Especially for the older Git versions, most of the suggestions won't work that well. If that's the case, I'd put a separate .gitignore in the directory where I want the content to be included regardless of other settings and allow there what is needed.

For example: /.gitignore

# ignore all .dll files
*.dll

/dependeny_files/.gitignore

# include everything
!*

So everything in /dependency_files (even .dll files) are included just fine.

Especially for the older Git versions, most of the suggestions won't work that well. If that's the case, I'd put a separate .gitignore in the directory where I want the content to be included regardless of other settings and allow there what is needed.

For example: /.gitignore

# ignore all .dll files
*.dll

/dependency_files/.gitignore

# include everything
!*

So everything in /dependency_files (even .dll files) are included just fine.