patch applied (ghc): Emit ' linking not required' messages only with -v 2 or above.

[Don Stewart]

Sun Jun 11 00:10:41 PDT 2006  Don Stewart <dons at cse.unsw.edu.au>
  * Emit 'linking not required' messages only with -v 2 or above.
  
  Similar in philosophy to the 'Skipping' patch, this is another case of
  printing noisy messages when no work is being done. This patch makes the
  building-when-nothing-to-do case smoother.
  

    M ./compiler/main/DriverPipeline.hs -1 +1