xorg-server: fix CVE-1940

http://lists.x.org/archives/xorg-devel/2013-April/036014.html
It's a low-priority issue, but it should cause almost no rebuilds.
pkgs/top-level/release-haskell.nix: re-structure Hydra job set

The new job set has the following structure:

  pkg.ghc762.x86_64-linux  = pkgs_x86_64_linux.haskellPackages_ghc762.pkg;
  pkg.ghc762.i686-linux    = pkgs_i686_linux.haskellPackages_ghc762.pkg;
  pkg.ghc6123.x86_64-linux = pkgs_x86_64_linux.haskellPackages_ghc6123.pkg;
  pkg.ghc6123.i686-linux   = pkgs_i686_linux.haskellPackages_ghc6123.pkg;

This gives us (in theory) the ability to generate a Hydra page that displays
the build status of a package across all versions of GHC and all systems. Right
now, Hydra is not up to it, but Eelco says the feature is "on the todo list".

This file doesn't specify the supported build systems explicitly. Instead, that
information is taken from the respective pkg.meta.platforms attribute.
obnam: Update to 1.4
gtk+: enable xcursor support, fixes #469

@vcunat also reorganized the build input lists a bit
haskell-digestive-functors-heist: update to version 0.6.2.0
haskell-hamlet: update to version 1.1.7.1
haskell-tagged: update to version 0.6
haskell-crypto-api: jailbreak to support current version of tagged
haskell-certificate: jailbreak to support current version of crypto-pubkey-types
haskell-ghc-vis: update to version 0.6.1.1
haskell-semigroups: update to version 0.9.1
haskell-skein: update to version 1.0.1
haskell-snap: update to version 0.11.2.2
haskell-fsnotify: update to version 0.0.8
haskell-statistics: update to version 0.10.3.1
haskell-wai-test: update to version 1.3.1
haskell-skein: jailbreak to support current version of 'tagged'
 haskell-haskeline: fix build with GHC 7.0.x
haskell-snap: jailbreak to fix build with 'hashable' and 'tagged'
Update Linux 3.9rc