gst1-validate: disable building documentation using sphinx
Fix a build failure in case (a non functional) sphinx documentation
system is installed on the host (reported [1] and fix tested [2]
by grunpferd@netscape.net).
Fixes:
sphinx-build -b html -d ./doctrees . ./html
Error: Source directory doesn't contain a conf.py file.
Signed-off-by: Peter Seiderer <ps.report@gmx.net> Cc: grunpferd@netscape.net
[Arnout:
- use --disable-sphinx-doc instead of a cv variable
- remove the comment, it speaks for itself] Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>