Fix the about-formatting.sh, syntax-highlighting.py and html-converters files.
* gnu/packages/version-control.scm (cgit)[arguments]: Include
about-formatting.sh and the html-converters in the patch-absolute-file-names
phase and add a wrap-python-scripts phase to wrap syntax-highlighting.py and
the md2html converter.
[inputs]: Add groff, python, python-docutils, python-markdown and
python-pygments.