babeltrace-cfg.c: do not infer text.text sink with -v

babeltrace-cfg.c: do not infer text.text sink with -v

Having the -v option passed to the `convert` command is not a
sufficient criterion to infer a text.text sink component, because -v
is also a general option which applies to the whole command. Without
this patch, you can't run this:

    babeltrace -v /path/to/trace -o my.sink

because the configurator sees both an implicit text.text sink (caused by
-v) and an explicit my.sink sink.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>