patch applied (ghc): FIX #1561: don't use tabs in pretty-printed output at all.

[Simon Marlow]

Wed Nov  7 03:32:01 PST 2007  Simon Marlow <simonmar at microsoft.com>
  * FIX #1561: don't use tabs in pretty-printed output at all.
  Tabs aren't guaranteed to be 8 spaces on every output device, so we
  shouldn't be using them.  Instead I added a little optimisation to
  use chunks of 8 spaces for long indentations.
  

    M ./compiler/utils/Pretty.lhs -4 +7