[GHC] #9812: Split `SynTyCon` into `SynonymTyCon` and `FamilyTyCon`

[GHC]

#9812: Split `SynTyCon` into `SynonymTyCon` and `FamilyTyCon`
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       Reporter:  jstolarek          |                   Owner:  jstolarek
           Type:  task               |                  Status:  new
       Priority:  low                |               Milestone:
      Component:  Compiler           |                 Version:  7.9
       Keywords:                     |        Operating System:
   Architecture:  Unknown/Multiple   |  Unknown/Multiple
     Difficulty:  Moderate (less     |         Type of failure:
  than a day)                        |  None/Unknown
     Blocked By:                     |               Test Case:
Related Tickets:                     |                Blocking:
                                     |  Differential Revisions:
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 As part of my work on #6018 I added new fields to `SynTyCon` data
 constructor of `TyCon` type. These fields only make sense for type
 families because we don't trace injectivity information for type synonyms.
 `SynTyCon` already has some fields that only make sense for type families.
 Richard suggests that `SynTyCon` is split into two separate constructors.
 With my implementation of injective type families this makes even more
 changes. I'm going to make that change in HEAD Real Soon Now so that I can
 rebase my work on top of it.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9812>
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