Previously, the various install paths were obtained using get_option
as needed.
This patch unifies the directory selection inside the top-level meson
file as requested in https://github.com/hughsie/colord/pull/62.
* Meson >=0.41.0, (unreleased) polkit 0.114+ don't use data_dirs argument
* Meson >=0.41.0, older polkit, use local ITS rules with data_dirs argument
* Meson <0.41.0, any polkit, use custom policy building rules
Later on when meson 0.41.0+ and polkit 0.114+ is in many stable distros
this commit can be reverted and dependencies updated.
Fixes: #107
Automake and autoconf are impossible to fully understand and Meson now provides
everything we need for a much smaller, faster, and more understandable build.
See http://mesonbuild.com/ for more information.
