QA Notice: Automake "maintainer mode" detected: cd . && /bin/bash /var/tmp/portage/media-plugins/alsa-plugins-1.0.20/work/alsa-plugins-1.0.20/missing --run aclocal-1.10 -I m4 cd . && /bin/bash /var/tmp/portage/media-plugins/alsa-plugins-1.0.20/work/alsa-plugins-1.0.20/missing --run automake-1.10 --foreign cd . && /bin/bash /var/tmp/portage/media-plugins/alsa-plugins-1.0.20/work/alsa-plugins-1.0.20/missing --run autoconf If you patch Makefile.am, configure.in, or configure.ac then you should use autotools.eclass and eautomake or eautoreconf. Exceptions are limited to system packages for which it is impossible to run autotools during stage building. See http://www.gentoo.org/proj/en/qa/autofailure.xml for more information.
I've fixed this myself since I was looking at alsa stuff (which I shouldn't by the way...).