After A problem to compile Gnome-Setup-tools, I found that autoconf in linked to autoconf 2.13 (with autoconf --version). But autoconf 2.53a is emerged (emerge -s autoconf) . I don't know why autoconf 2.13 is still installed as 2.53a is here. I try to to make emerge clean, without success.
Duplicate of the bug 11336, sorry