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

[GHC]

#8683: add "cpp program" and "cpp program options" to settings file
-------------------------------------+------------------------------------
        Reporter:  carter            |            Owner:
            Type:  feature request   |           Status:  patch
        Priority:  normal            |        Milestone:  7.8.1
       Component:  Compiler          |          Version:  7.7
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:  #8439
-------------------------------------+------------------------------------

Comment (by joelteon):

 It seems like this patch hardcodes /usr/bin/gcc to be the compiler during
 the build of in-tree ghc-pwd, which results in a lot of build-related
 headaches on OSX, since /usr/bin/gcc is clang pretending to be gcc.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8683#comment:18>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler