[GHC] #8683: add "cpp program" and "cpp program options" to settings file

[GHC]

#8683: add "cpp program" and "cpp program options" to settings file
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        Reporter:  carter            |            Owner:
            Type:  feature request   |           Status:  new
        Priority:  highest           |        Milestone:  7.8.1
       Component:  Compiler          |          Version:  7.8.1-rc2
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:  #8439
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Comment (by carter):

 so current status of my branch:

 * the build system currently needs some love to handle none gcc/clang CPP,
 (and fails in way i'm not very good at understanding when i try using
 cpphs).  It seems --with-gcc=gcc-4.8 --with-hs-cpp=clang works, i'm in the
 midst of testing that and the opposite presently

 * subject being build with one of those two, we can then patch the
 settings file to point to cpphs and the resulting configered GHC passes
 the test suite


 I factor the latter as its own patch? That seems valuable for us now, the
 former isnt quite as key, though we shoudl figure it out..

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8683#comment:41>
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