zfs-utils*/: add explicit --enable-systemd

It should already be installed, but makechrootpkg might non-conformantly
not have it installed leading to broken system probing. Short-circuit
the check entirely.

Also clean up some autotools path args that were already the default.

PKGBUILD

@@ -39,13 +39,11 @@ build() {
                 --sysconfdir=/etc \
                 --sbindir=/usr/bin \
                 --with-mounthelperdir=/usr/bin \
-                --libdir=/usr/lib \
-                --datadir=/usr/share \
-                --includedir=/usr/include \
                 --with-udevdir=/usr/lib/udev \
                 --libexecdir=/usr/lib/zfs \
                 --with-python="$PWD/python3-fake" \
                 --enable-pyzfs=no \
+                --enable-systemd \
                 --with-config=user
     make
 }