fixing up links to commits and ghc source on trac wiki/trackers

[Edward Z. Yang]

Hi Carter,

The reason the links are broken is because the Git Trac plugin is currently
disabled for performance reasons.  The easiest thing to do is to get the
plugin updated and re-enable it.

Edward

Excerpts from Carter Schonwald's message of Fri May 24 10:52:44 -0700 2013:
> Hey all,
> 
> Currently the commit/ source file links on trac wiki and tickets are all
> dead, and while thats not a problem for active ghc devs and such, it does
> create more friction for new users.
> 
> My understanding is the previously the file and commit references would
> point at a haskell.org repository, would it be worth having them point at
> the github analogues thereof? (and for that matter would that be easy to
> do, or take up more of the finite ghc dev time?)
> 
> (in my tickets or the like, i'm by hand doing ghc file / commit links to
> github to make it easier for myself and others to look up the relevant
> info.)