patch applied (ghc): Bugfix to iterative coalescer

[Ben Lippmeier]

Mon Sep 17 05:42:41 PDT 2007  Ben.Lippmeier at anu.edu.au
  * Bugfix to iterative coalescer
  
  Coalescences must be applied to the unsimplified graph in the same order 
  they were found by the iterative coalescing algorithm - otherwise
  the vreg rewrite mapping will be wrong and badness will ensue.

    M ./compiler/nativeGen/RegAllocColor.hs -6 +7
    M ./compiler/nativeGen/RegAllocStats.hs -2 +7
    M ./compiler/utils/GraphColor.hs -2 +2
    M ./compiler/utils/GraphOps.hs -3 +5