[PATCH libinput 00/13] Enable parallel testing

[Peter Hutterer]

A current test run takes anywhere north of 30 minutes on a good machine.
Much of that time is spent either rebuilding the hwdb or just waiting for
various timeouts. 

We run the tests in serial to avoid interference between the various udev
rules. Running the current set in parallel has some interesting side effects
(mostly the ID_INPUT_* labelling being wrong when the udev hwdb is refreshed
at the wrong time).

This set allows for parallel testing by:
03: moving all the tests into a single binary
04: dumping the udev rules in place once at start 
09: forking off like crazy to run the variuos tests in different processes 

So we don't actually use parallel make check, we just do the parallel stuff
ourselves. A normal test run is now down to about 3-4 min, a full suite
hovers around 7-8 min.

The tests are distributed by group name across the processes, I suspect some
more time can be gained by better distribution (or even a test queue) but
for now the reduction is pretty great anyway.

Cheers,
  Peter