Fix a stack exhaustion bug in libiberty's demangler when decoding a pathalogically constructed mangled name.

	PR 89394
	* cp-demangle.c (cplus_demangle_fill_name): Reject negative
	lengths.
	(d_count_templates_scopes): Replace num_templates and num_scopes
	parameters with a struct d_print_info pointer parameter.  Adjust
	body of the function accordingly.  Add recursion counter and check
	that the recursion limit is not reached.
	(d_print_init): Pass dpi parameter to d_count_templates_scopes.
	Reset recursion counter afterwards, unless the recursion limit was
	reached.

From-SVN: r270258