patch applied (ghc): Use update-alternatives for handling generic tool names

[Malcolm Wallace]

Sven Panne <Sven.Panne at aedion.de> wrote:

>        Alas, this doesn't work well with the Haskell
>        implementations yet, because they come with different sets of
>        tools (in addition to runFOO):
>   
>          GHC:  hsc2hs
>          Hugs: hsc2hs, cpphs
>          nhc:  cpphs

nhc98 does actually ship with hsc2hs, but it currently gets used only
during building.  It is not installed, in order to avoid conflict with
the ghc-shipped tool of the same name.

>   runhaskell are created via update-alternatives now. What is
>   currently missing is a mechanism for platforms like Windows and
>   probably Mac OS X.

Is 'update-alternatives' a command name?  If so, I can confirm that it
doesn't exist on MacOS X.  Probably something like the gcc_select
mechanism would be needed to switch between default compilers.  (But I
don't know how that is implemented.)

Regards,
    Malcolm