ccache and distcc, take two

Hi all,
  this is a second attempt at getting autoconf/automake to understand
our desire to get builds faster, and this attempt works for me.

I'm attaching a patch for 2.6S2, please check it out. Forward-porting to
3.0 should be trivial, I'll commit to that as soon as I get feedback on
this one.

Don't forget to bootsrap.sh after applying.

        Kinkie