targets/xorg: Install lts-saucy drivers on precise for Haswell support
targets/xorg: Install lts-saucy drivers on precise for Haswell support

We first pull in `lts-saucy` replacement drivers, then `xorg`:
- Doing it in that order still pulls in `xorg` dependencies like
  `xterm` and `xinit`, and avoids the need to specify them manually.
- Removing ``--minimal`` from the `lts-saucy` line also works, but
  also pulls in stuff like an updated kernel, which we don't want.
- Installing `xorg` after `lts-saucy` does not install old drivers
  (so there is no useless download).
- On existing chroots, installing `lts-saucy` uninstalls old drivers,
  and marks a number of packages as not required, like `xterm` and
  `xinit` (which would be cleaned later by autoclean). Reinstalling
  `xorg` does not install new packages, but makes sure these packages
  are not autocleaned.

twmccart/crouton,VandeurenGlenn/crouton,nromsdahl/crouton,JDGBOLT/chroagh,arbuztw/crouton,dragon788/chroagh,taterbase/crouton,djmrr/crouton,dnschneid/crouton,mkasick/crouton,arbuztw/crouton,ikaritw/crouton,elkangaroo/chroagh,jamgregory/crouton,StrawnPoint04/crouton,twmccart/crouton,dnschneid/crouton,fxcebx/crouton,brayniac/crouton,mkasick/crouton,taterbase/crouton,stephen-soltesz/crouton,DanDanBu/crouton,nromsdahl/crouton,ikaritw/crouton,stephen-soltesz/crouton,tedm/crouton,rperce/chroagh,elkangaroo/chroagh,stephen-soltesz/crouton,armgong/chroagh,dnschneid/crouton,brayniac/crouton,mkasick/crouton,rperce/chroagh,marriop/newCrouton,tedm/crouton,VandeurenGlenn/crouton,Timvrakas/crouton,fxcebx/crouton,StrawnPoint04/crouton,ikaritw/crouton,elkangaroo/chroagh,zofuthan/crouton,JDGBOLT/chroagh,VandeurenGlenn/crouton,dragon788/chroagh,armgong/chroagh,tonyxue/cruise,VandeurenGlenn/crouton,zofuthan/crouton,zofuthan/crouton,DanDanBu/crouton,armgong/chroagh,djmrr/crouton,rperce/chroagh,tedm/crouton,taterbase/crouton,ikaritw/crouton,tonyxue/cruise,rperce/chroagh,zofuthan/crouton,jamgregory/crouton,arbuztw/crouton,dragon788/chroagh,marriop/newCrouton,JDGBOLT/chroagh,fxcebx/crouton,twmccart/crouton,twmccart/crouton,nromsdahl/crouton,Timvrakas/crouton,zofuthan/crouton,mkasick/crouton,elkangaroo/chroagh,StrawnPoint04/crouton,elkangaroo/chroagh,taterbase/crouton,twmccart/crouton,djmrr/crouton,tedm/crouton,tonyxue/cruise,jamgregory/crouton,nromsdahl/crouton,fxcebx/crouton,marriop/newCrouton,jamgregory/crouton,brayniac/crouton,mkasick/crouton,brayniac/crouton,DanDanBu/crouton,JDGBOLT/chroagh,ikaritw/crouton,brayniac/crouton,tonyxue/cruise,Timvrakas/crouton,dragon788/chroagh,JDGBOLT/chroagh,jamgregory/crouton,tonyxue/cruise,Timvrakas/crouton,StrawnPoint04/crouton,VandeurenGlenn/crouton,jamgregory/crouton,arbuztw/crouton,dragon788/chroagh,rperce/chroagh,Timvrakas/crouton,stephen-soltesz/crouton,tedm/crouton,DanDanBu/crouton,tedm/crouton,tonyxue/cruise,rperce/chroagh,twmccart/crouton,zofuthan/crouton,dnschneid/crouton,taterbase/crouton,armgong/chroagh,nromsdahl/crouton,DanDanBu/crouton,stephen-soltesz/crouton,dnschneid/crouton,fxcebx/crouton,fxcebx/crouton,armgong/chroagh,Timvrakas/crouton,mkasick/crouton,arbuztw/crouton,DanDanBu/crouton,armgong/chroagh,elkangaroo/chroagh,JDGBOLT/chroagh,VandeurenGlenn/crouton,djmrr/crouton,dnschneid/crouton,brayniac/crouton,nromsdahl/crouton,djmrr/crouton,StrawnPoint04/crouton,djmrr/crouton,ikaritw/crouton,stephen-soltesz/crouton,StrawnPoint04/crouton,arbuztw/crouton,dragon788/chroagh,taterbase/crouton