Add support for CircleCI

Add support for CircleCI

This isn't currently hooked up to the fdo repo but it's hooked up to my
github mirror. I had SemaphoreCI hooked up to that before but it only
supports ubuntu 14.04 and the recent meson switch made it a bit hard to setup.

CircleCI supports running docker containers, so let's do that and run against
the most recent released Fedora and a recent Ubuntu. I'm not bothering with
rawhide, it's likely to increase the work for little gain when it's in a
semi-broken state.

Run the default build with a few permutations to test meson options. Run
scan-build too but that's just for the logs, eventually this may turn into a
hard failure.

Ubuntu 17.04's meson is too old, so we have to clone that from git. Install
arguments are taken from the meson.deb package.

Most of this effort was done by Benjamin Tissoires.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Cc: Benjamin Tissoires <benjamin.tissoires@gmail.com>