[GHC] #7761: iOS patch no 16: pass the correct -Dxxx_HOST_ARCH and -Dxxx_HOST_OS to hsc2hs by stage

[GHC]

#7761: iOS patch no 16: pass the correct -Dxxx_HOST_ARCH and -Dxxx_HOST_OS to
hsc2hs by stage
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Reporter:  StephenBlackheath  |          Owner:                  
    Type:  feature request    |         Status:  new             
Priority:  normal             |      Component:  Compiler        
 Version:  7.7                |       Keywords:                  
      Os:  Unknown/Multiple   |   Architecture:  Unknown/Multiple
 Failure:  None/Unknown       |      Blockedby:                  
Blocking:  7724               |        Related:                  
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 Currently hsc2hs always gets the build host's values, even when cross
 compiling. This patch makes it pass the correct values for the stage.

 There is no actual build failure that results from this being wrong, but
 it is only a matter of time before something breaks.

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7761>
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