meson ground rules!

[Michael Catanzaro <mcatanzaro gnome org>]

Hi,

Some GNOME modules have started to experiment with switching to the
meson build system instead of Autotools. Personally, I want to
encourage this; even though as a project we haven't come to any
consensus on whether we want to do a wholesale migration to meson, I
think it's starting to look likely as its advantages over Autotools and
CMake are pretty clear to me. But we still need to make sure it's easy
for contributors to build GNOME. So a couple ground rules for this from
release team:

 * Projects using meson are encouraged (although not required) to
continue maintaining the Autotools build in parallel for GNOME 3.24 as
meson continues to mature. We will consider recommending the removal of
Autotools builds in the GNOME 3.26 timeframe.

 * Projects that choose to remove the Autotools build system must not
require meson newer than 0.34.0. We'll set a higher permissible version
requirement for GNOME 3.26 next spring.

 * Make sure your module builds in JHBuild. Important: do not switch
JHBuild to use the meson module type until you have released a tarball
that includes the meson build system.

 * For GNOME 3.24, make sure your module builds in Continuous. You'll
have to add a patch that adds a fake configure script and a fake
Makefile. I do not believe this requirement is desirable going forward
-- if we do a large scale switch to meson, then Continuous is just
going to have to learn to grok our new build system -- but let's not
break it now.

Thanks for helping make sure our release process goes smoothly,

Michael