iptables: improve runit services.

If the rules files don't exist just return... this way the runsvdir log
is not cluttered with ENOENT messages.
lxdm: start X in tty7 without systemd.
New package: dunst-1.1.0.
iptables: services: return -> exit just for correctness.
New package: xfce4-xkb-plugin-0.5.6 from equeim in #680.

Close #680. Thanks!
fdm: update to 1.8.
libosmocore: update to 0.7.0.
colord-gtk: update to 0.1.26.
mpv: update to 0.7.1.
ntp: update to 4.2.7p482.
unrar: update to 5.2.3.
New package: libgksu-2.0.12
librsvg: update to 2.40.6.
New package: gksu-2.0.2
New package: caja-extensions-common-1.8.0
afl: update to 0.85b (close #682).
Revert "build_style/gnu-makefile: use our compiler/linker flags."

This reverts commit e5cc2819b460b20cdbf498e30e7c39791956538e.

Revert this for now... Makefile writers don't seem to respect them.
xtools: update to 0.11.
xtools: update checksum.
nss: update to 3.17.3.