checking for compiler -fshort-wchar option... yes
checking whether to enable C++ RTTI... no
checking whether we have a gtk 2 gecko build... configure: error: This program needs a gtk 2 gecko build

!!! Please attach the following file when filing a report to bugs.gentoo.org:
!!! /var/tmp/portage/yelp-2.15.91/work/yelp-2.15.91/config.log

!!! ERROR: gnome-extra/yelp-2.15.91 failed.
Call stack:
  ebuild.sh, line 1543:   Called dyn_compile
  ebuild.sh, line 938:   Called src_compile
  ebuild.sh, line 1252:   Called gnome2_src_compile
  gnome2.eclass, line 63:   Called gnome2_src_configure
  gnome2.eclass, line 59:   Called econf '--enable-man' '--enable-info' '--with-mozilla=seamonkey' '--disable-gtk-doc'
  ebuild.sh, line 539:   Called die

!!! econf failed
!!! If you need support, post the topmost build error, and the call stack if relevant.

!!! This ebuild is from an overlay: '/usr/local/overlays/gnome'