Add a script to check for Sphinx install requirements

Sphinx installation is not trivial, as not all versions are supported, and it requires a lot of stuff for math, images and PDF/LaTeX output to work.

So, add a script that checks if everything is fine, providing distro-specific hints about what's needed for it to work.

I posted already RFC patches for the first patch in this series along this weekend at linux-doc ML. The current version of the script will provide hints for some popular distributions. I tested myself on a couple of release-based and rolling popular distributions:

- Fedora 25 and 26;
- Ubuntu 17.04;
- OpenSuse Tumbleweed;
- Arch Linux;
- Gentoo.

I tested compilation with both htmldocs and pdfdocs targets[1]. Yet, tests (and fix patches) are welcomed :-)

Those patches are at:

https://git.linuxtv.org/mchehab/experimental.git/log/?h=sphinx_install_v2

PS.:

1) The first patch in this series is actually independent: it is just a cleanup from DocBook removal patches.

2) Debian 17.04 version of ImageMagick seems capped:
it can't read SVG texts with things like:
font-family="'Liberation Sans', Sans"
It also doesn't handle other random SVG tags. So, I had to rewrite several media SVG files to make them more compliant with ImageMagick.

So far, I can't submit those patches via e-mail, as some lines there are bigger than 998 characters, with violates VGER rules for maximum number of columns. I'll try to break the big lines there via some scripting.

-

v2: be sure that GraphViz and ImageMagick will generate PDF
outputs on all platforms but OpenSuse (where GraphViz is built without PDf support).

Mauro Carvalho Chehab (8):
docs: Makefile: remove no-ops targets scripts/sphinx-pre-install: add a script to check Sphinx install
sphinx-pre-install: detect an existing virtualenv
sphinx-pre-install: use a requirements file
sphinx-pre-install: check for the need of graphviz-gd
sphinx-pre-install: add dependencies for ImageMagick to work with svg
sphinx-pre-install: fix USE needs for GraphViz and ImageMagick sphinx.rst: document scripts/sphinx-pre-install script

 Documentation/Makefile                 |  10 -
 Documentation/doc-guide/sphinx.rst     |  48 ++-
 Documentation/sphinx/requirements.txt  |   3 +
 Documentation/translations/zh_CN/HOWTO |   2 -
 Makefile                               |   2 +-
 scripts/sphinx-pre-install             | 544 +++++++++++++++++++++++++++++++++
 6 files changed, 592 insertions(+), 17 deletions(-)
 create mode 100644 Documentation/sphinx/requirements.txt
 create mode 100755 scripts/sphinx-pre-install

2.13.3