Rewrite GLR parser to catch more buffer overrun, storage exhaustion,

Rewrite GLR parser to catch more buffer overrun, storage exhaustion,
and size overflow errors.
* data/glr.c: Include <stdio.h> etc. after user prolog, not before,
in case the user prolog sets feature-test macros like _GNU_SOURCE.
(YYSIZEMAX): New macro.
(yystpcpy): New function, taken from yacc.c.
(struct yyGLRStack.yyspaceLeft): Now size_t, not int.
(yyinitGLRStack, yyfreeGLRstack): Remove unnecessary forward decls,
so that we don't have to maintain their signatures.
(yyFail): Check for buffer overflow, by using vsnprintf rather
than vsprintf.  Allocate a bigger buffer if possible.
Report an error if buffer allocation fails.
(yyStackOverflow): New function.
(yyinitStateSet, yyinitGLRStack): Return a boolean indicating whether
the initialization was successful.  It might fail if storage was
exhausted.
(yyexpandGLRStack): Add more checks for storage allocation failure.
Use yyStackOverflow to report failures.
(yymarkStackDeleted, yyglrShift, yyglrShiftDefer, yydoAction):
(yysplitStack, yyprocessOneStack, yyparse, yypstack):
Don't assume stack number fits in int.
(yysplitStack): Check for storage allocation failure.
(yysplitStack, yyprocessOneStack): Add pure_formals, so that we
can print diagnostics on storage allocation failure.  All callers
changed.
(yyresolveValue): Use yybool for boolean.
(yyreportSyntaxError): Check for size-calculation overflow.
This code is taken from yacc.c.
(yyparse): Check for storage allocation errors when allocating
the initial stack.