The problem was created by a tweak that was implemented to address Bug #27064. A sed statement hardcoded a static library path using the /usr/lib directory, when get_libdir should have been used. I've attached two patches for both the 4.2.x series and the 4.3.x series. Mamoru, let me know if you approve and I can actually committ for you if you'd like.
Created attachment 86883 [details, diff] zsh-4.2.6-r1.ebuild.patch
Created attachment 86884 [details, diff] zsh-4.3.2-r1.ebuild.patch
I've committed both patches. I'll give it a few days then close the bug.
One complaint and it was addressed; bug is closed!