[GHC] #13477: Turn cIntegerLibraryType into a dynflag

[GHC]

#13477: Turn cIntegerLibraryType into a dynflag
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           Reporter:  nomeata        |             Owner:  (none)
               Type:  task           |            Status:  new
           Priority:  low            |         Milestone:
          Component:  GHC API        |           Version:  8.1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 Currently, at configure time we tell GHC whether integers are built using
 `integer-gmp` or `integer-simple`, and this gets baked in via the global
 constant `cIntegerLibraryType`.

 This is all fine for normal use of GHC (the program), but users of ghc
 (the library) might want to have more leeway here.

 A good solution seems to be turn this into a dynflag setting, so that
 users of the GHC API can adjust that as fit. From a cursory glance at the
 code, this does not seem to be a big problem.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13477>
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