[WiP] gtk-doc: patch the on-line DocBook XSL paths to the local #56504
This is what's done in Guix, so
Motivation for this change
Cleaning up, robustness.
The [WiP] tag is because I couldn't test the impact on the other packages due to the limits of my hardware and Internet connection, and also because much of those packages fail for the deprecation warnings, not sure what that means.
This is what's done in Guix, so `gtkdoc-mkhtml` would in no case even try to reach for the Internet. Also removed `dblatex`, because it was never enabled and causes circular dependencies if it is. The `--disable-scrollkeeper` configure flag isn't recognized by now. And `doCheck` should be left alone, as long as the tests pass.
The URI is, in the first place, an identifier of the stylesheet; the method the stylesheet will be obtained is independent of this. The primary source for locating the resources is the XML catalog; the fact that the URI can be used as a web URL is secondary and should not bother us – we, as packagers, are responsible for making the proper catalogs available.
I like the idea of limiting the scope where docbook-xsl is available to gtk-doc. In nixpkgs, sometimes the runtime dependencies of build tools are made available through dependencies of the depending package. This is usually done when the dependency is only used for a specific subsystem of the build tool (e.g. PDF generation) and we do not want to increase the closure of the tool for people who only need HTML export. However, since DocBook support will almost always be used, adding the stylesheet as a direct dependency to gtk-doc makes sense.
I am not very fond of patching over the URI with store path directly, though. I would rather rely on the catalogs still (perhaps using