Corret initconfdir substitution for some distros

Not every Linux distro is using @sysconfdir@/default but the correct
path is already determined by configure. Let's use it.

Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>

contrib/initramfs/hooks/zfs.in

@@ -12,7 +12,7 @@ COPY_EXEC_LIST="@sbindir@/zdb @sbindir@/zpool @sbindir@/zfs"
 COPY_EXEC_LIST="$COPY_EXEC_LIST @mounthelperdir@/mount.zfs @udevdir@/vdev_id"
 COPY_EXEC_LIST="$COPY_EXEC_LIST @udevdir@/zvol_id"
 COPY_FILE_LIST="/etc/hostid @sysconfdir@/zfs/zpool.cache"
-COPY_FILE_LIST="$COPY_FILE_LIST @sysconfdir@/default/zfs"
+COPY_FILE_LIST="$COPY_FILE_LIST @DEFAULT_INITCONF_DIR@/zfs"
 COPY_FILE_LIST="$COPY_FILE_LIST @sysconfdir@/zfs/zfs-functions"
 COPY_FILE_LIST="$COPY_FILE_LIST @sysconfdir@/zfs/vdev_id.conf"
 COPY_FILE_LIST="$COPY_FILE_LIST @udevruledir@/60-zvol.rules"