[GHC] #13189: Implement same specification as GHC spec file for mingw32

[GHC]

#13189: Implement same specification as GHC spec file for mingw32
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           Reporter:  Phyx-          |             Owner:  Phyx-
               Type:  feature        |            Status:  new
  request                            |
           Priority:  normal         |         Milestone:  8.4.1
          Component:  Compiler       |           Version:  8.0.1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:  #13093
Differential Rev(s):                 |         Wiki Page:
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 When the `GCC` driver envokes the pipeline a `SPEC` is used to determine
 how
 to configure the compiler and which libraries to pass along.

 For Windows/mingw, this specfile is
 https://github.com/gcc-mirror/gcc/blob/master/gcc/config/i386/mingw32.h

 This has a lot of interesting things that we need to emulate in order to
 be able to link as many things out of the box as GCC. In particular this
 is why you never need to specify `-lgcc_s` when compiling, but you do when
 using `GHCi`.

 Or specifying what `-mwindows` links in, that when `-lstdc++` is used what
 else to link in. Which base DLLs GCC will always link with when building
 an exe.

 And how to link `libgcc`, either static or dynamically.

 Currently we only support static linking of `libgcc` (which maybe we
 should change? or at least make user changeable).

 The current partial implementation works by adding hooks into the RTS. A
 better implementation is adding it all outside the RTS in the
 `DriverPipeline` tied directly to the commandline options.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13189>
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