As in semantic actions, make @$ in %initial-action, %destructor, and

As in semantic actions, make @$ in %initial-action, %destructor, and
%printer imply %locations.
* src/scan-code.l (SC_SYMBOL_ACTION): Set locations_flag = true when
scanning @$.
* tests/actions.at (AT_CHECK_ACTION_LOCATIONS): New macro supporting...
(@$ in %initial-action implies %locations,
@$ in %destructor implies %locations,
@$ in %printer implies %locations): ... these new test cases.