Define NS5::GObject#signal_connect_data only once during testing. This avoids redefinition warnings.
Define NS5::GObject#signal_connect_data only once during testing.
This avoids redefinition warnings.

jcupitt/gir_ffi,mvz/gir_ffi,mvz/gir_ffi,jcupitt/gir_ffi,mvz/gir_ffi