[GHC] #5743: Configurably use system-provided libffi

[GHC]

#5743: Configurably use system-provided libffi
---------------------------------+------------------------------------------
    Reporter:  nomeata           |       Owner:  trommler    
        Type:  feature request   |      Status:  patch       
    Priority:  normal            |   Milestone:  7.6.2       
   Component:  Build System      |     Version:  7.2.1       
    Keywords:                    |          Os:  Linux       
Architecture:  Unknown/Multiple  |     Failure:  None/Unknown
  Difficulty:  Unknown           |    Testcase:              
   Blockedby:                    |    Blocking:              
     Related:  #4496             |  
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Changes (by trommler):

  * status:  new => patch


Comment:

 The patch validates on Linux with and without the new flag {{{--with-
 system-libffi}}}. Please validate on MacOS and Windows before pushing. I
 tried to validate on MacOS but failed to compile ghc-7.6 branch without
 the patch.

 The patch adds three flags to configure:

 {{{--with-system-libffi}}}  use system provided libffi

 {{{--with-ffi-includes}}}   find includes for libffi in non-standard
 directory

 {{{--with-ffi-libraries}}}  find libraries for libffi in non-standard
 directory

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5743#comment:9>
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