Disable exec symlink resolution for PostgreSQL 9.2

When building PostgreSQL with plugins under NixOS, NixOS will create a
postgresql-and-plugins directory which symlinks PostgreSQL and all the plugins
into a single directory. Unfortunately, the plugins will not actually be usable
by PostgreSQL because it will still try and locate them in the original
PostgreSQL share directory, not postgresql-and-plugins.

In this commit, I have patched resolve_symlinks to always return success, which
matches the behavior if HAVE_READLINK is false (so presumably invalid paths are
never passed to this function).
nixos/nginx: allow to specify which package to use

This enables to override which plugins to include with nginx by allowing to change
nginx package. I also removed webdav option in nginx nixos module, because you
can now specify this by overriding nginx package.
Attempt at compiling MilkyTracker, but recent zlib version may have broken it.

There's a zlib version included with milkytracker,
but there's no makefiles for it. I've only included
the header here, but it fails at link-time with
several 'undefined reference' errors, which simply
means it can't find the definitions, e.g. compiled
zlib.
There's bug reports on other package systems although
unfortunately still unresolved.
https://bugs.archlinux.org/task/31324
http://lists.freebsd.org/pipermail/freebsd-ports/2013-March/082180.html
MilkyTracker: fix build, use system zlib and decompressor patch

Also add JACK support
MilkyTracker: Tidy up, sort buildInputs and use the attrPath for the license
fetchsvn: handle redirect(s)

Instead of failing if the server redirects us to a new URL, accept up to
2 redirects by printing 2 extra p's to subversion.
varnish: adding version 2.1.x
ejabberd: updated to 2.1.13
pythonPackage: afew and alot update to latest

added subprocess32 package as new dependency of afew
haskell-wxc: noHaddock
venus.nix: Fix broken startAt option
Make touchpad button mapping configurable
mathematica: fix x86 build of mathematica

the MathInstaller doesn't distinguish between 64bit and 32bit linux
platforms.
quodlibet: update to version 2.6.3

also provides two distinctive flavours, which either wrap the program to
pull in the gstreamer plugins or not.
afew: forgot to add --replace
Linux 3.12 release

Signed-off-by: Shea Levy <shea@shealevy.com>
fcron: Fix error when cron.mailto is null.

Signed-off-by: Moritz Ulrich <moritz@tarn-vedra.de>
redshift: add platforms
Merge pull request #1163 from kowey/haskell-wx

haskell-wxc: noHaddock
Add serverFlagsSection parameter to the xserver config