Catch modules that don't set all the function pointers.

Catch modules that don't set all the function pointers.

For the "not initialized" functions, check if the pcap_t is activated
and, if so, report a regular error, with an error message of "This
operation isn't properly handled by that device".  ("Properly handled"
always includes "providing a function for it, even if it fails because
that function can't work on the device".)