build-sys: autotools: Add meson build files to EXTRA_DIST

As we currently still generate our tarballs using autotools, let's make
sure the meson build system is distributed with the tarball.
2 jobs for v12.99.2 in 5 minutes and 36 seconds (queued for 8 seconds)
latest
Status Job ID Name Coverage
  Build
passed #477696
build-autotools

00:05:14

passed #477697
build-meson

00:01:38