gstreamer: Add support for Meson as alternative/parallel build system

[Tim-Philipp Müller]

On Sun, 2016-08-21 at 10:53 +0200, Stefan Sauer wrote:

Hi Stefan,

>  FYI: the autotools based build can be made a lot faster by switching
> to non recursive make. Especially on the plugin modules the gains are
> large. If we could make up our mind on this subject, it would be a
> matter for a few devs of dedicating one evening and switching.

I'm aware of that, but the faster build on Linux is really just a
pleasant side-effect in this case, it was not the primary goal here.
And I suspect ninja will still be faster than non-recursive make. 

I don't think moving to non-recursive make is worth the hassle though,
it's just applying more layers of lipstick.

In any case, I'll write a mail about this all soon, let's discuss it
more then :)

Cheers
 -Tim