Improve SELinux support by introducing subdirs and by changing the order of the intermediate file locations

Submitted by Fabian Deutsch

Link to original bug (#735871)

Description

This bug also exists here:
https://bugs.freedesktop.org/show_bug.cgi?id=41446

To help writing selinux rules for orc two changes are introduced:

1. Use a subdir for intermediate files
2. Change the order of potential locations for the intermediate files

The attached patches add this functionality.