It seems a c++ source was not configured out
Created attachment 366906 [details] bug_info.tar.xz info/log files
should be all set now in the tree; thanks for the report! Commit message: Control libasprintf (a C++ library) via USE=cxx http://sources.gentoo.org/sys-devel/gettext/gettext-0.18.3.1-r1.ebuild?r1=1.3&r2=1.4