At this point meson is pretty well tested and seems to pretty much work,
so we can consider dropping an extra build system.
This doesn't solve the problem that pixman's release scripts are part of
the autotools build system (as make targets). One solution might be to
use xorg's release.sh instead.
Ben Avison pointed out here:
http://lists.freedesktop.org/archives/pixman/2013-January/002485.html
that there isn't really any documentation about how to submit patches
to pixman. This patch adds some information to the README file.
v2: Incorporate some comments from Ben Avison
v3: Change gitweb URL to cgit
