socate: Update to 1.7.2.2, 2.0.0-b6

CVE-2013-3571
apache-httpd: Update to 2.4.6
Remove some unsupported platforms
Don't build some packages on some platforms
Allow packages to be marked as "broken" by setting meta.broken

The effect is that they won't show up in "nix-env -qa" anymore.
Don't build Linux 3.6-rpi packages on Hydra

They're all broken.
Mark more packages as broken
Remove broken and obsolete versions of gcj and ghdl