Improve test-pangocairo-threads
Improve test-pangocairo-threads

Can be run standalone now, compares the output of all threads and fails
if they mismatch.

danny-ku/pango,Distrotech/pango,kari-lentz/alpha-pango,kari-lentz/alpha-pango,Distrotech/pango,kari-lentz/alpha-pango,danny-ku/pango,Distrotech/pango,kari-lentz/alpha-pango,danny-ku/pango