fix pangomm build: use cairo 1.12.2
wicd: wrapper env vars prefix -> postfix

Change PATH=$PATH:deps to PATH=deps:$PATH in the wicd wrappers, because
the latter is more deterministic; it prevents possibly wrong versions of
dependencies to sneak in from the environment.

Do the same for PYTHONPATH.
linux: Don't put the kernel version in meta
Unify the Linux kernel configurations

Having N different copies of the NixOS kernel configuration is bad
because these copies tend to diverge.  For instance, our 3.10 config
lacked some modules that were enabled in older configs, probably
because the 3.10 config had been copied off an earlier version of some
older kernel config.

So now there is a single kernel config in common-config.nix.  It has a
few conditionals to deal with new/removed kernel options, but
otherwise it's pretty straightforward.

Also, a lot of cut&paste boilerplate between the kernel Nix
expressions is gone (such as preConfigure).
iwlwifi4965ucodeV1: Remove

This is verrrry obsolete.
linux: Disable /dev/kmem

See e.g.
  https://wiki.ubuntu.com/Security/Features#A.2BAC8-dev.2BAC8-kmem_disabled
linux: Remove some unused patches
linux: Remove CIFS timeout patch

We longer use CIFS in the VM tests so we don't need this anymore.
linux: Remove obsolete AUFS 3.7 patch
Style fix
linux: Enable stack protector

This may prevent exploitation of buffer overflows.
linux: Enable detection of hung tasks
linux: Include "NixOS" in "uname -v"
- System images are not required for building. Disabling them makes building faster.
- Make ant flags configurable
Shut up annoying question to configure hardware profiles
Turn LD_LIBRARY_PATH into a suffix to allow NVIDIA's OpenGL driver to be used
Move kernelExtraConfig to common-config.nix (for x86)

It's bad to have the kernel config scattered across two places.  (This
should also be done for the other architectures.)

Also, restore Xen and KVM guest support in Linux 3.10.
VM builds: Use the default kernel
VM builds: Reduce kernel verbosity
git: Update to 1.8.3.4