Add support for meson
A few 7 year old patches that never made it upstream, followed by some cleanups and support for meson. Building XIT now just comes down to
$ git submodule init $ git submodule update $ meson build && ninja -C build test
Some tests fail, but they do with the autotools build too, so...
Reverts the tuple patch because of #1 (closed)
Requires xorg-gtest!4 (merged)