xorg/util/modular: merge request (find_vpython.sh)

[tlaronde at kergis.com]

I have added a POSIX.2 utility: find_vpython.sh, that can be used
to search for a python interpreter matching a required version (the
version is optional; if given, it is:

op major [minor [micro]]

op: '<' | '<=' | '==' | '>=' | '>'

It verifies PYTHON in the environment (to match what Autotools
configure does); if not set, it list all the '^python[0-9.]*$' that
are in the PATH and test them against the version condition.

If found, the pathname of the highest matching version is returned and
then, after a space, the pythondir (subdir) to put third parties
module in.

It is to be used from meson.build (an example will follow in
xcb-proto) and the utility has to be copied in the module dir.

But it can be used independantly (for the ones not using Meson).

Note: I will finally push this week the Meson work for xcb-proto, and publish a
whole page online with explanations, chunk by chunk, about the process of
writing the meson files.
-- 
        Thierry Laronde <tlaronde +AT+ kergis +dot+ com>
                     http://www.kergis.com/
                    http://kertex.kergis.com/
                     http://nunc-et-hic.fr/
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