* data/bison.simple (yydestructor): Pass it the current location
if locations are enabled.
Prototype only when __STDC__ or C++.
Change the argument names to move into the yy name space: there is
user code here.
* data/bison.simple.new (yyerrlab1): Be sure to pop and destroy
what's left on the stack when the error recovery hits EOF.
* tests/actions.at (Destructors): Complete to exercise this case.
arguments is really empty, not only equal to `[]'.
* src/symtab.h, src/symtab.c (symbol_t): `destructor' is a new
member.
(symbol_destructor_set): New.
* src/output.c (symbol_destructors_output): New.
* src/reader.h (brace_code_t, current_braced_code): New.
* src/scan-gram.l (BRACED_CODE): Use it to branch on...
(handle_dollar): Rename as...
(handle_action_dollar): this.
(handle_destructor_dollar): New.
* src/parse-gram.y (PERCENT_DESTRUCTOR): New.
(grammar_declaration): Use it.
* data/bison.simple (yystos): Is always defined.
(yydestructor): New.
* tests/actions.at (Destructors): New.
* tests/calc.at (_AT_CHECK_CALC_ERROR): Don't rely on egrep.
* src/reader.c (readgram): Be sure to attach mid-rule actions to
the empty-rule associated to the dummy symbol, not to the host
rule.
* tests/actions.at (Mid-rule actions): New.
