Make it easy to get hyperlinked sources
Make it easy to get hyperlinked sources

The version of `haddock` that ghc has as a submodule has an option
for generating linkified sources. I don't think it hurts to have this
and they are great for exploring the codebase.

I'd be nice if harbormaster or travis published them somewhere, but
I don't know how to do that yet.

Test Plan:
uncomment, run `make` and look at the
nicely linkified sources in `compiler/stage2/doc/html/ghc/`

Reviewers: hvr, austin, bgamari

Reviewed By: bgamari

Subscribers: thomie, simonmar

Differential Revision: https://phabricator.haskell.org/D2119

vTurbine/ghc,olsner/ghc,shlevy/ghc,snoyberg/ghc,vikraman/ghc,ezyang/ghc,sdiehl/ghc,sdiehl/ghc,vikraman/ghc,vikraman/ghc,tjakway/ghcjvm,sgillespie/ghc,ezyang/ghc,shlevy/ghc,tjakway/ghcjvm,mettekou/ghc,sdiehl/ghc,ezyang/ghc,snoyberg/ghc,sdiehl/ghc,mettekou/ghc,tjakway/ghcjvm,snoyberg/ghc,mettekou/ghc,sgillespie/ghc,tjakway/ghcjvm,shlevy/ghc,sgillespie/ghc,sgillespie/ghc,vTurbine/ghc,vikraman/ghc,olsner/ghc,olsner/ghc,sdiehl/ghc,ezyang/ghc,vTurbine/ghc,vTurbine/ghc,vikraman/ghc,olsner/ghc,sgillespie/ghc,sdiehl/ghc,shlevy/ghc,snoyberg/ghc,shlevy/ghc,vTurbine/ghc,sgillespie/ghc,sgillespie/ghc,snoyberg/ghc,olsner/ghc,mettekou/ghc,ezyang/ghc,sdiehl/ghc,vTurbine/ghc,vTurbine/ghc,snoyberg/ghc,ezyang/ghc,olsner/ghc,mettekou/ghc,shlevy/ghc,tjakway/ghcjvm,mettekou/ghc,olsner/ghc,tjakway/ghcjvm,shlevy/ghc,tjakway/ghcjvm,ezyang/ghc,vikraman/ghc,snoyberg/ghc,vikraman/ghc,mettekou/ghc