debian/rules: Drop -Bsymbolic(-functions)

GNOME Tracker tests fail with -Bsymbolic(-functions) as reported upstream in https://gitlab.gnome.org/GNOME/tracker/issues/78. The problem is that both libtracker-data and libtracker-sparql are linked to a static library that contains the symbol tracker_sparql_connection_get_type. Because libtracker-sparql depends on libtracker-data, we end-up having a duplicate symbol.

Drop -Bsymbolic(-function) for the moment to fix autopkgtest.