sp-compat: Fix build

You can't run fixupPhase before installPhase.

http://hydra.nixos.org/build/8149119
fixupPhase: Handle the case where $prefix doesn't exist

http://hydra.nixos.org/build/8149154
add arpack-3.1.4
add build-lsb-chrootenv
add vobsub2srt-git-20131228-1c782e5
add mathematica-9.0.1
Build numpy against openblas
Don't set a default version of Mathematica

Nixpkgs should not set a default version of Mathematica. Many users of
Mathematica have institutional licenses and do not have immediate access
to new versions. If there is a default version in Nixpkgs, updating that
version will cause trouble for all such users.
Don't set shells as default whenever enabled

Because alternative shells like Zsh are almost non-functional unless
"enabled", it doesn't make sense to try setting them as default just
because they are enabled.
Merge branch 'installed' of github.com:ttuegel/nixpkgs into installed