smurf: Have MAKEMAP write OUTFILES also for ITER

When MAKEMAP is not making tiles and is run with METHOD=ITERATE
it should now write the name of the (single) output file to the
file specified by OUTFILES.  It seems reasonable for it to do
this because it does so for METHOD=REBIN and the documentation
for OUTFILES doesn't mention that it doesn't work for
METHOD=ITERATE unless tiles are being made.