[2.10..2.13] Backport updated font paths

Update fonts for Debian and openSUSE

• Allow to read conf-avail dir itself.
• Add various openSUSE-specific font config directories.

See merge request !96 (merged) for details.

(cherry picked from commit 7bd3029f)

b902d250 Update fonts for Debian and openSUSE

I propose this patch for 2.10..2.13