All ${STDERR_TARGET} occurences in .* > ${STDERR_TARGET.*}.* should be quoted. Also, epunt_cxx could be changed to support spaces in ${S}.
Created attachment 140721 [details] ../dev/space_patches/eutils.eclass-spaces.patch Patch to fix epunt_cxx and an occurence of EPATCH_SOURCE.
i already had that epatch locally, but forgot to commit it ... should be in cvs now http://sources.gentoo.org/eclass/eutils.eclass?r1=1.293&r2=1.294