I just ran the vdkbuilder ebuild and was surprised when it built libvdk. I can't really explain this as it seems the ebuild SHOULD be building vdkbuilder. Odd thing is that vdkbuilder needs a copy of vdk to build... wait just found it. They used a sed-like ebuild command. Please make dev-util/vdkbuilder either dev-libs/vdk or dev-libs/libvdk. I'll submit an ebuild within the next day or so for vdkbuilder to this bug.
Created attachment 3034 [details] x11-libs/vdk-2.0.2
Created attachment 3035 [details] dev-util/vdkbuilder-2.0.3
Those both compiles quite well on my system. You may want to check it on yours.