patch applied (ghc): Refactor MachRegs.trivColorable to do unboxed accumulation

[Ben Lippmeier]

Wed Sep  5 05:52:19 PDT 2007  Ben.Lippmeier at anu.edu.au
  * Refactor MachRegs.trivColorable to do unboxed accumulation
  
  trivColorable was soaking up total 31% time, 41% alloc when
  compiling SHA1.lhs with -O2 -fregs-graph on x86.
  
  Refactoring to use unboxed accumulators and walk directly
  over the UniqFM holding the set of conflicts reduces this 
  to 17% time, 6% alloc.

    M ./compiler/nativeGen/AsmCodeGen.lhs -2 +2
    M ./compiler/nativeGen/GraphBase.hs -1 +1
    M ./compiler/nativeGen/GraphOps.hs -2 +2
    M ./compiler/nativeGen/MachRegs.lhs -6 +78
    M ./compiler/nativeGen/RegAllocColor.hs -4 +5
    M ./compiler/nativeGen/RegAllocLinear.hs +1
    M ./compiler/utils/UniqFM.lhs -1 +2