This should probably go to the portage team. The ebuild does: eautoconf -o configure-libafs configure-libafs.ac and the output of autoconf in /var/tmp/portage/net-fs/openafs-kernel-1.6.22.2/temp/autoconf-1.out is: ***** PWD: /var/tmp/portage/net-fs/openafs-kernel-1.6.22.2/work/openafs-1.6.22.2 ***** autoconf -o configure-libafs configure-libafs.ac -I //usr/share/aclocal autoconf-2.69: error: invalid number of arguments Try `autoconf-2.69 --help' for more information. So it seems that eautoreconf now (I'm using sys-apps/portage-2.3.33) adds "-I //usr/share/aclocal" at the end of the autoconf arguments, which it doesn't understand.
Now that portage is at 2.3.36 it works again. Closing.