directfb: bump to version 1.4.13

There's an even newer stable release available (1.4.14), but it
has problems with cross-compilation that we are still resolving
on the directfb-dev mailing-list.

[Peter: rename ppc patch to match]
Signed-off-by: Sven Neumann <s.neumann@raumfeld.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>