I recently updated Apache 2.2.4 to -r4 and it start to complain about unknown directive SuExecUserGroup. Then I founded that <IfDefine SUEXEC> block somehow disappeared from httpd.conf (as it was present there in later 2.2.4). I tried to delete httpd.conf and reemerge apache but still without any success. Adding "LoadModule mod_suexec modules/mod_suexec.so" somewhere to confs solved the problem but I think this is a bit confusing. Reproducible: Always
Your solution is the right one, but you looked at the wrong place ;) The main reason is the ebuild lacking a mods="${mods} suexec" line, which is needed to add the LoadModule to httpd.conf in src_install. I've just committed a fix for that to the ebuild and if you remerge apache once the rsync mirrors have the new version of apache-2.2.4-r4, you should have that fix.
