Make glcean parameters consistent with other functions

[sandr01d]

Check list

• [X] I have performed a self-review of my code
• [ ] I have commented my code in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation

Description

Most functions try to pass parameters directly to git and exit early when successfull. _forgit_clean is an exception to this, as it currently only uses the arguments to determine the target files. Our completions use _git-clean, which completes untracked files, but gclean -f FILE currently opens the file picker. I've added a line to allow an early out for _forgit_clean.

Type of change

• [ ] Bug fix
• [X] New feature
• [ ] Refactor
• [ ] Breaking change
• [ ] Documentation change

Test environment

• Shell
  • [X] bash
  • [X] zsh
  • [X] fish
• OS
  • [X] Linux
  • [ ] Mac OS X
  • [ ] Windows
  • [ ] Others: