patch applied (ghc): Writing out .tix file only if you are the original process, not a child.

[Andy Gill]

Mon Sep 17 16:06:41 PDT 2007  andy at galois.com
  * Writing out .tix file only if you are the original process, not a child.
  This lets us gain coverage on programs that use fork, like xmonad.
  
  * To be merged to STABLE *
  

    M ./rts/Hpc.c -2 +11