from p3. Some shells leave PWD in the environment (old tcsh, ksh at least)

from p3. Some shells leave PWD in the environment (old tcsh, ksh at least)
screws nested configures. "unset PWD" is the right answer, except that
Decstation sh doesn't *have* unset.
	Note also that the send-pr build will fail if you have PWD in your
environment, because emacs also (foolishly) trusts it.

	* configure: just set PWD=`pwd` at the top, since Ultrix sh
	doesn't have unset and all success paths (and most error paths)
	out set it anyway. (Note: should change all uses of ${PWD=`pwd`}
	to just ${PWD} to avoid confusion.)