Your package is runtime-depending on app-doc/doxygen standing to http://tinderbox.dev.gentoo.org/misc/rindex/app-doc/doxygen . app-doc/doxygen is a tool used almost always at build-time, (it's either a build system or a generator - sorry this is a generic template I start with so I can't tell you right away which one). This means that it should only be depended at build-time.
Please correct your ebuild or document why it is used as a runtime-dependency so that it will not be suspected again.
Hmm, it doesn't build with GCC 4.3, when adding the missing includes I get warnings that make me suspect the code is broken, the last release on sourceforge is from 2005, it's not used by anything in the tree except vdkbuilder. I think this would be a good time to remove it, unless anyone wants to do the work to get this in better shape.
The patch from here https://launchpad.net/ubuntu/+source/vdk2/2.4.0-5.1 does allow 4.0 to compile with gcc 4.3.3 on amd64
CCing treecleaners as vdkbuilder will also go and is the only consumer
Author: Michał Górny <email@example.com>
AuthorDate: Sun Jul 24 12:49:28 2016
Commit: Michał Górny <firstname.lastname@example.org>
CommitDate: Sun Jul 24 12:52:44 2016
dev-libs/vdk: Remove last-rited pkg, #221667