CI improvements

1. Add -doc packages of dependencies to hopefully get links to them in
the generated documentation.

2. Build libchamplain just once with gtk enabled and build both
gtk and non-gtk documentations.
2 jobs for master in 1 minute and 27 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
failed #209834
build-champlain

00:01:27

 
  Deploy
skipped #209835
pages
 
Name Stage Failure
failed
build-champlain Build

Complete!
$ dnf install -y glib2-devel glib2-doc clutter-devel clutter-doc gtk3-devel gtk3-doc clutter-gtk-devel clutter-gtk-doc cairo-devel cairo-doc sqlite-devel libsoup-devel gobject-introspection-devel
Last metadata expiration check: 0:00:54 ago on Fri Feb 8 21:16:48 2019.
No match for argument: gtk3-doc
No match for argument: clutter-gtk-doc
No match for argument: cairo-doc
Error: Unable to find a match
ERROR: Job failed: exit code 1