The ebuild has the line: ppc64? ( sys-devel/automake )" but x86 also needs automake installed to be able to build. Replace with: sys-devel/automake and it builds. By the way, it's not the greatest idea to update ebuilds without also updating the release number, as I see the previous ebuild was also called "-r5".
Fixed. Revision bumps are only needed when a change would be sufficiently beneficial to someone who has already installed the package (see http://www.gentoo.org/doc/en/policy.xml)