The proposed solution is in the tracker. If this is an autotools based package, and '--disable-silent-rules' doesn't work, you can try to add MAKEOPTS+=" V=1"
+ 17 Nov 2012; Pacho Ramos <pacho@gentoo.org> -libcanberra-0.28-r5.ebuild, + libcanberra-0.29.ebuild: + Disable silent rules, #443132 by ago. +