Update gnome-chess to 3.12.3. Remove the PRCTL hack (which involved
the removal of src/chess-engine.c) that was fixed after the
release of 3.12.2. [1], [2]

[1] https://bugzilla.gnome.org/show_bug.cgi?id=729042
[2] gnome-chess commit f2f2842bff233d2e


git-svn-id: svn://creme-brulee.marcuscom.com/ports/trunk@19759 df743ca5-7f9a-e211-a948-0013205c9059