package/dvdauthor: fix static build

Dvdauthor forget to link witk -lbz2 when linking with freetype2.

Fixes:
http://autobuild.buildroot.net/results/1d8/1d83390a3dd9f6bb595e9fc7b321500b4dc533a8/



Signed-off-by: Romain Naour <romain.naour@openwide.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>