Drop autotools

It's been a few releases that we ship Meson support, we should be
able to drop the old autotools build system now.

Signed-off-by: Simon Ser <contact@emersion.fr>
3 jobs for main in 3 minutes and 3 seconds (queued for 50 seconds)
Status Name Job ID Coverage
  Review
passed check-commit #15633659

00:00:24

 
  Containers Build
passed container_build #15633660

00:02:04

 
  Test
passed test-meson #15633661

00:00:34