Add meson support
A few cleanups followed by support for the meson build system.
This is the MVP, there may be flags in the autotools system that meson doesn't support yet but given this project is unmaintained anyway.. meh. This version works with the equivalent patch in the xorg-integration-tests, see xorg-integration-tests!3 (merged)
cc @p12tic
Edited by Peter Hutterer