patch configure.ac to use System.Directory.getCurrentDirectory

Also generate configure from configure.ac

This fixes the error,

<interactive>:2:1:
    Failed to load interface for `Directory'
    It is a member of the hidden package `haskell98-2.0.0.1'.
    Use -v to see a list of the files searched for.

We could also try adding the -package haskell98 flag, but that gives:

Top level:
    Ambiguous interface for `Prelude':
      it was found in multiple packages: base haskell98-2.0.0.1

Author: Jeremy Shaw