There is a patch for this in arch: https://aur.archlinux.org/packages/mod_scgi
+*mod_scgi-1.14-r1 (09 May 2015) + + 09 May 2015; Pacho Ramos <pacho@gentoo.org> + +files/mod_scgi-1.14-apache-2.4.patch, +mod_scgi-1.14-r1.ebuild: + Support apache 2.4 (#532866) +