[RFC PATCH] build: add meson build system

[David Bremner]

Jani Nikula <jani at nikula.org> writes:

> This is a draft patch adding basic configure, build and test support
> for the binaries. Everything else is left out for now. It would be a
> considerable amount of work to convert everything, and I don't expect
> it to be possible in one go anyway. If there's interest in adding
> meson support, it would have to happen gradually, side-by-side with
> the current system, with a reasonably long transition period. But
> there's no point in going beyond the patch at hand if folks decide the
> focus should remain on the current system.

Personally I think the idea is worth pursuing, but I admit I don't have
much experience with meson/ninja.  How much churn can we expect from
meson changes? It seems there is something like one meson point release
per month.

Are the tests supposed to be working fully in this version? When I run

% meson && cd build && ninja && ninja test

I get failures in T010, T351, T356, T357, T391, T395, and T710.  At a
glance it looks like mainly out-of-tree related problems to finding
e.g. json_check_nodes.py and message-id-parse. It also looks like a few
variables like TEST_RUBY and NOTMUCH_HAVE_PYTHON3_CFFI are not being
set.

d