A patch to add --with-oldest-abi=ABI. [Re: A patch to add --disable-old-version.]

[Ulrich Drepper]

I have applied this patch now although I'm still not 100% satisfied:

- res_init is not handled correctly

- applications using the old interfaces start up with the reduced library
  and will crash later.  This really has to be avoided.  Looking through
  all the undefined references at runtime is probably unwanted.

  It might be OK to make all the functions which are currently completely
  gone to be aliases of a function which prints an error message and then
  terminates the application.  So we at least don't get such an anonymous
  death.

  Even better would be a solution which would signal the problems at
  startup time.  It might be possible to require that the youngest version
  in the application is the same or an even younger one then the version
  number given to the --with-oldest-abi option.

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Ulrich Drepper  \    ,-------------------'   \  Sunnyvale, CA 94089 USA
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