Merge request: xcbproto Meson added, CI passed

[tlaronde at kergis.com]

The support for Meson has been added, and the CI builds and checks
Autotools vs. Meson builds.

The byte-compilation of Python modules generates identical files due
to:
	- DESTDIR correct support in the (added) compile_py.sh (note:
	python compileall module doesn't work correctly);

	- Python support for SOURCE_DATE_EPOCH, allowing (in the CI
pipeline) to define a global such variable and then to obtain this
date in the byte-compiled versions in two distinct jobs running at
differing times;

The generated pc files are compared using the (added)
xorg/util/modular/auto-meson-pc-cmp.sh, that compares the results
semantically and not literally.

The doc here:

https://notes.kergis.com/x11_building.html

has been updated with the correct version of the CI instructions.
-- 
        Thierry Laronde <tlaronde +AT+ kergis +dot+ com>
                     http://www.kergis.com/
                    http://kertex.kergis.com/
                     http://nunc-et-hic.fr/
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