Upgrading the standard initial environment

For Nix on i686-linux we make use of an environment of statically linked
tools (see $nixpkgs/stdenv/linux). The first version of these tools were
compiled outside of Nix, in an impure environment. They are used as some
magical ingredient to make everything work. To keep these tools more in
synchronization with the rest of nixpkgs and to make porting of nixpkgs
to other platforms easier the static versions are now also built with Nix
and nixpkgs.

The tools can be found in nixpkgs in:

- shells/bash-static
- tools/networking/curl-diet
- tools/archivers/gnutar-diet
- tools/compression/gzip-diet
- tools/text/gnused-diet
- tools/text/diffutils-diet
- tools/text/gnupatch-diet
- tools/misc/findutils-static
(still missing: bzip2)

Most packages are compiled with dietlibc, an alternate C library, apart
from bash and findutils, which are statically linked to glibc. The reason
we chose dietlibc has various reasons. First of all, curl cannot be built
statically with glibc. If we do, we get a static binary, but it cannot resolve
hostnames to IP addresses. glibc dynamically loads functionality at runtime
to do resolving. When linking with dietlibc this doesn't happen.

The static tools are not used as part of the input hashing (see Eelco's
PhD thesis, paragraph 5.4.1), so changing them does not change anything and
will not force a massive rebuild.
