patch applied (ghc): Check inplace doesn't exist before we try to create it

[Ian Lynagh]

Fri Sep 24 12:18:58 PDT 2010  Ian Lynagh <igloo at earth.li>
  * Check inplace doesn't exist before we try to create it
  This fixes rerunning configure in a tree which already has an inplace
  directory. Edward Z Yang ran into this; I guess whether it actually
  fails depends on details of your installation, or we'd have run into
  it sooner.

    M ./configure.ac -1 +1

View patch online:
http://darcs.haskell.org/cgi-bin/darcsweb.cgi?r=ghc;a=darcs_commitdiff;h=20100924191858-3fd76-197eb25dd31bdf830fd28e30c6c504a87a935695.gz