parse.lac: implement exploratory stack reallocations.

parse.lac: implement exploratory stack reallocations.

* data/yacc.c: Rename %define variable parse.lac.es-capacity to
parse.lac.es-capacity-initial.  Accept parse.lac.memory-trace
with values of "failures" (default) or "full".
(b4_declare_parser_state_variables): Add yyesa, yyes, and
yyes_capacity variables.
(YYSTACK_USE_ALLOCA): Ignore it if LAC requested.
(YYSTACK_ALLOC, YYSTACK_FREE, YYSTACK_ALLOC_MAXIMUM): Define if
LAC requested.
(YYCOPY_NEEDED): New cpp macro.
(YYCOPY): Define if LAC requested.
(yy_lac_stack_realloc): New function implementing stack
reallocations.  Use YYMAXDEPTH for maximum stack size given that
the stack should never need to grow larger than the main state
stack needs to grow without LAC.
(YY_LAC_ESTABLISH): Update yy_lac invocation.
(yy_lac): Add arguments for exploratory stack memory data
recorded in the main parser.  Invoke yy_lac_stack_realloc when
reallocation is necessary.
(yysyntax_error): Add the same new arguments and pass them to
yy_lac.
(yypstate_delete): Free yyes if necessary.
(yyesa, yyes, yyes_capacity): #define these to yypstate members
in the case of push parsing.
(yyparse, yypush_parse): Initialize yyes and yyes_capacity.
Update yysyntax_error invocations.  At yyreturn, free yyes if
necessary.
* src/parse-gram.y: %define parse.lac full.
* tests/input.at (LAC: errors for %define): Extend for
parse.lac-memory-trace.
* tests/regression.at (LAC: Exploratory stack): Extend to check
that stack reallocs happen when expected.
(LAC: Memory exhaustion): Update to use YYMAXDEPTH and
parse.lac.es-capacity-initial.