Rebuild config files if Makefile changes.

This ensures paths are updated if they are changed by re-running configure.
Patch from rapier at psc.edu.

Makefile.in

@@ -296,7 +296,7 @@ $(MANPAGES): $(MANPAGES_IN)
 		$(FIXPATHSCMD) $${manpage} | $(FIXALGORITHMSCMD) > $@; \
 	fi
 
-$(CONFIGFILES): $(CONFIGFILES_IN)
+$(CONFIGFILES): $(CONFIGFILES_IN) Makefile
 	conffile=`echo $@ | sed 's/.out$$//'`; \
 	$(FIXPATHSCMD) $(srcdir)/$${conffile} > $@