Fix a destructor bug reported by Wolfgang Spraul in

Fix a destructor bug reported by Wolfgang Spraul in
<http://lists.gnu.org/archive/html/bug-bison/2005-05/msg00042.html>.
* data/yacc.c (yyabortlab): Don't call destructor, and
don't set yychar to EMPTY.
(yyoverflowlab): Don't call destructor.
(yyreturn): Call destructor, if yychar is neither YYEOF nor YYEMPTY.
* tests/calc.at (AT_CHECK_CALC): Expect one fewer output lines,
since we no longer output the message "discarding lookahead token
end of input ()".