Meson is a modern build system that has seen a rise in adoption and some
version of it is available in almost every platform supported.
Compared to automake, meson has the following advantages:
* Meson provides a significant boost to the build and configuration time
by better exploiting parallelism.
* Meson is subjectively considered to be better in readability.
These merits alone justify experimenting with meson as a way of
improving development time and ergonomics. However, there are some
compromises to ensure the transition goes relatively smooth:
* The system tests currently rely on various files within the source
directory. Changing this requirement is a non-trivial task that can't
be currently justified. Currently the last compiled build directory
writes into the source tree which is in turn used by pytest.
* The minimum version supported has been fixed at 0.61. Increasing this
value will require choosing a baseline of distributions that can
package with meson. On the contrary, there will likely be an attempt
to decrease this value to ensure almost universal support for building
BIND 9 with meson.
The system tests were overriding the local locale by setting LANG to C.
This does not override the locale in case there are individual LC_<*>
variables like LC_CTYPE explicitly set.
Use LC_ALL=C instead which is the proper way of overriding all currently
set locales.
Remove conf.sh.in and move the environment variables into isctest/vars
python package. This enabled the removal of an ugly pytest hack which
loaded and parsed these variables from the environment.
