Do not hardcode Wall
Currently there are warning flags hardcoded in the meson.build:
add_project_arguments('-Wall', '-Wundef', language: 'c')
This should not be done IMHO as meson has the
warning_level builtin option to control compiler
warning granularity and will probably get more fine-grained options for this in the future,
possibly making our hardcoded options conflict with the ones selected by the user.
Instead what we can do is set a different default for