pkg-config --libs fontconfig does not contain -lexpat. This is not noticed when linking dynamically, but when linking static it is needed.
It lacks -lfreetype aswell on my system
Furter... pkg-config gtk+-2.0 (x11 target) does not depend on pangoft2, so if you try to link in static, -lpango lacks it's backend. If you want to compile any gtk+-2.0 program statically now you need do the following currently `pkg-config gtk+-2.0 pangoft2 --libs` -static -lexpat (Also... this depends on atk being compiled with static support which is not possible with the current atk ebuild.... I fiddled with it some does ago.. I recall it was atk that was lacking that. It might have been another package, but that is not relevant for these problems)
I added a somewhat crude pkgconfig fix for this to fontconfig-2.3.2-r1 . Thanks for the report.