tools: Include stdio.h in gupnp-dlna-info.c
tools: Include stdio.h in gupnp-dlna-info.c

We need it for fprintf(), but somehow this didn't turn up as a warning
on any of our systems.

GNOME/gupnp-dlna,GNOME/gupnp-dlna,luisbg/gupnp-dlna,GNOME/gupnp-dlna,luisbg/gupnp-dlna