Reduce the verbosity of makewhatis -t:

Reduce the verbosity of makewhatis -t:
In the past, it always showed the title lines of the files processed.
Now, it only shows them when called with -D.
That is better because pkg_create calls makewhatis -t.
It is also more consistent with -D behaviour in non- -t modes.
Issue reported by ajacoutot@; ok espie@ ajacoutot@ jasper@.