The upstream currently ships with both a Makefile and a Makefile.qt.

The default build approach would be to re-make the Makefile from the
.qt template, but in fact the Makefile has been manually tuned by 
upstream.  Therefore I keep the orignal Makefile and prevent DH from
invoking removing the Makefile on cleanup.

Not sure if this was the "best" fix but it's the easiest.

-- Tim Booth <tbooth@ceh.ac.uk> Aug 2012
