Remove hard-coded path to pwd; there is no need to have it, and for example
NixOS doesn't actually have it at this location, leading to such an error:

    ./configure: line 36: /bin/pwd: No such file or directory
    /qtbase/configure not found. Did you forget to run "init-repository"?

Change-Id: If3372db3390ba5f39c5003d12ff2a466f39ff353
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>