[GHC] #10705: make configure warn when ghc-tarballs is missing on windows and provide guidance to download it.

[GHC]

#10705: make configure warn when ghc-tarballs is missing on windows and provide
guidance to download it.
-------------------------------------+-------------------------------------
        Reporter:  Phyx-             |                   Owner:
            Type:  task              |                  Status:  new
        Priority:  normal            |               Milestone:  7.12.1
       Component:  Build System      |                 Version:  7.11
      Resolution:                    |                Keywords:
Operating System:  FreeBSD           |            Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:  #9218             |  Differential Revisions:  Phab:D1108
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Comment (by Phyx-):

 It seems that the configure script doesn't force any particular
 environment.
 On windows it was always using bash so didn't notice.

 Whatever shell the freebsd one is using doesn't seem to like functions.
 I will inline the function calls to fix this.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10705#comment:5>
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