SCC analysis for instances as well as types/classes

This big patch is in pursuit of Trac #11348.

It is largely the work of Alex Veith (thank you!), with some
follow-up simplification and refactoring from Simon PJ.

The main payload is described in RnSource
  Note [Dependency analysis of type, class, and instance decls]
which is pretty detailed.

* There is a new data type HsDecls.TyClGroup, for a strongly
  connected component of type/class/instance/role decls.

  The hs_instds field of HsGroup disappears, in consequence

  This forces some knock-on changes, including a minor
  haddock submodule update

Smaller, weakly-related things

* I found that both the renamer and typechecker were building an
  identical env for RoleAnnots, so I put common code for
  RoleAnnotEnv in RnEnv.

* I found that tcInstDecls1 had very clumsy error handling, so I
  put it together into TcInstDcls.doClsInstErrorChecks

2 files changed, 2 insertions, 1 deletions

diff --git a/utils/ghctags/Main.hs b/utils/ghctags/Main.hs
index 0eff514b70..ba116b6bd4 100644
--- a/utils/ghctags/Main.hs
+++ b/utils/ghctags/Main.hs
@@ -256,7 +256,8 @@ boundValues mod group =
                        , bind <- bagToList binds
                        , x <- boundThings mod bind ]
                _other -> error "boundValues"
-      tys = [ n | ns <- map (fst . hsLTyClDeclBinders) (tyClGroupConcat (hs_tyclds group))
+      tys = [ n | ns <- map (fst . hsLTyClDeclBinders)
+                            (hs_tyclds group >>= group_tyclds)
                 , n <- map found ns ]
       fors = concat $ map forBound (hs_fords group)
              where forBound lford = case unLoc lford of
diff --git a/utils/haddock b/utils/haddock
-Subproject 5c82c9fc2d21ddaae4a2470f1c375426968f19c
+Subproject 56dbfe17d272670e5f2d082401c025755796950