[PATCH] doc: ensure sphinx output is reproducible

[Thomas Monjalon]

29/06/2023 14:58, christian.ehrhardt at canonical.com:
> From: Christian Ehrhardt <christian.ehrhardt at canonical.com>
> 
> By adding -j we build in parallel, to make building on multiprocessor
> machines more effective. While that works it does also break
> reproducible builds as the order of the sphinx generated searchindex.js
> is depending on execution speed of the individual processes.
[...]
> -if Version(ver) >= Version('1.7'):
> -    sphinx_cmd += ['-j', 'auto']

What is the impact on build speed on an average machine?