Third-party files of gtk-doc licensed under the terms of GNU GPLv3+, copyright provided by James Henstridge and Stefan Sauer

* gtk-doc.make (GPLv3+)

Third-party files of gtk-doc permissive licensed see specific files for warranty disclaimer and a notice preservation requirement, copyright provided by James Henstridge, Damon Chaplin and Stefan Sauer

* git.mk

Third-party files of gtk-doc licensed under the terms of GNU GPLv3+, copyright provided by Stefan Sauer

* Makefile.am (GPLv3+)
