Meson: Let recipes define cross compilation properties
Meson: Let recipes define cross compilation properties

With autoconf we used to define variables like glib_cv_stack_grows in
the environ, but with meson those variables needs to be defined inside
the cross-file we generate. For example GLib will be using those
properties: https://bugzilla.gnome.org/show_bug.cgi?id=794898.

https://bugzilla.gnome.org/show_bug.cgi?id=789316

GStreamer/cerbero,nirbheek/cerbero,centricular/cerbero,fluendo/cerbero,nirbheek/cerbero,centricular/cerbero,atsushieno/cerbero,nirbheek/cerbero,GStreamer/cerbero,GStreamer/cerbero,atsushieno/cerbero,fluendo/cerbero,centricular/cerbero,nirbheek/cerbero,fluendo/cerbero,fluendo/cerbero,centricular/cerbero,fluendo/cerbero,atsushieno/cerbero,centricular/cerbero,GStreamer/cerbero,atsushieno/cerbero,atsushieno/cerbero,GStreamer/cerbero