data-device: Change resources in wl_data_offer and wl_data_source to pointers.

Because of its links to selection.c and xwayland, a destroy_signal field
was also added to wl_data_source.  Before selection.c and xwayland were
manually initializing the resource.destroy_signal field so that it could be
used without a valid resource.

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
4 files changed