Verified on OS X 10.9.2 to build and check, dependents build fine too.

@vcunat enabled doCheck as it works for him on x86_64-linux;
also did style nitpick modification, and changed platforms to .all
according to the homepage http://www.swig.org/compat.html

@vcunat fixed syntax a bit. Close #2761.

We were one directory too high for configure.

Closes #2746

$ nix-env -f . -qa '*' --meta --xml --drv-path --show-trace
error: while querying the derivation named `clementine-1.2.1':
while evaluating `optional' at .../lib/lists.nix:113:20, called from .../pkgs/applications/audio/clementine/default.nix:50:22:
undefined variable `not' at .../pkgs/applications/audio/clementine/default.nix:50:32

nixos: add 'gvfs' when using GNOME3 desktop

clementine: disable unfree dependencies by default

renpy: update to 6.17.6

seafile: update client, ccnet, libsearpc and shared

update moc

mpd: fix build on darwin

For some reason library paths are not set at all for some libraries during
the build. Wrapper with LD_LIBRARY_PATH set for relevant libraries is currently
solution.

One reason for adding this is to make Chromium able to open files it has
downloaded.

Currently this happens:
  /run/current-system/sw/bin/xdg-open: line 364: gnome-open: command not found

(And nothing happens in the GUI when clicking a downloaded file.)

Looking into xdg-open, one can see that it first tries to run gvfs-open
and then falls back to gnome-open. Adding 'gvfs' makes the first command
succeed.

Clementine has an optional dependency on libspotify, which is unfree.
Enabling libspotify unconditionally prevented Hydra from distributing
Clementine. Now, we optionally enable it based on
config.clementine.spotify.

The file $out/mkspecs/qconfig.pri contains a list of all include /
library paths used during the build, including build-time-only
packages like GDB and Ruby. So get rid of those.

Building the tests (which as far as I can tell we don't even run)
makes the build take > 19 GiB of disk space, which is a bit
excessive. Without the tests, it takes 2.6 GiB.