pull module blacklist from Ubuntu and use it by default

People often have serious problems due to bogus modules like *fb.
lightdm: Update to 1.8.6
lightdm-gtk-greeter: Update to 1.6.1
kmod-blacklist-ubuntu: fetch from tar.gz, not bazaar

Now the source is just a miniature archive.
kmod-blacklist-ubuntu: fix references to binaries
dhcpcd: Update to 6.2.1

Dhcpcd now has integration with udev, so it should no longer be a
problem if udev renames an interface while dhcpcd is running.
Adding missing unistd.h includes
Update libcangjie 1.1
lttng-tools: use absolute path to modprobe

Instead of relying on it being available in $PATH.
hub: Update from 1.10.6 -> 1.11.1
Add pycangjie

[Bjørn Forsman <bjorn.forsman@gmail.com>: expression cleanup]
siege: Update to 3.0.6
siege: expression cleanup
nixos/nscd: add option to change nscd config

[Bjørn Forsman <bjorn.forsman@gmail.com>:
 - use types.lines instead of types.string. The former joins strings
   with "\n" and the latter with "" (and is deprecated).
]
Merge #1618: use ubuntu module blacklists by default
Merge #1645 and #1646: lightdm and -gtk-greeter update
switch-to-configuration.pl: Handle successful auto-restarts

switch-to-configuration.pl is currently hard-coded to assume that if a
unit is in the "auto-restart" state that something has gone wrong, but
this is not strictly true. For example, I run offlineimap as a oneshot
service restarting itself every minute (on success). NixOS currently
thinks that offlineimap has failed to start as it enters the
auto-restart state, because it doesn't consider why the unit failed.

This commit changes switch-to-configuration.pl to inspect the full
status of a unit in auto-restart state, and now only considers it failed
if the ExecMainStatus is non-zero.
Update/fix farstream: Gajim now at least builds
Fix wvdial build by inserting missing unistd.h includes
Create an attribute for latest ocaml packages even when this is not the default version