Looks like there are patches at: https://github.com/matsumoto-r/mod_extract_forwarded_for_2.4/commits/master
+*mod_extract_forwarded-2.0.3_pre2015052015 (09 May 2015) + + 09 May 2015; Pacho Ramos <pacho@gentoo.org> + +mod_extract_forwarded-2.0.3_pre2015052015.ebuild: + Support apache 2.4 (#532824) +