The latest version of autogen, according to the downloads directory at http://ftp.gnu.org/gnu/autogen/?C=M;O=D is 5.17.3. The announcements at http://www.gnu.org/software/autogen/announce.html agree. The version 5.15 currently in portage is over a year old. Current GNU sharutils (from git checkout) apparently requires the die and fserr functions added in 5.16, which is what got me started on this.
I successfully emerged a newer version by 1. copying the current ebuild, 2. removing the NOTES file from the dodoc invocation and 3. addressing bug 465370, although this should be unrelated.
should be all set now in the tree; thanks for the report! Commit message: Version bump http://sources.gentoo.org/sys-devel/autogen/autogen-5.17.3.ebuild?rev=1.1 http://sources.gentoo.org/sys-devel/autogen/metadata.xml?r1=1.4&r2=1.5