C99 test suite readiness: Some unverified test case adjustments

C99 test suite readiness: Some unverified test case adjustments

These changes are assumed not to interfere with the test objective,
but it was not possible to reproduce the historic test case failures
(with or without the modification here).

gcc/testsuite/

	* gcc.c-torture/compile/20000105-1.c: Add missing int return type.
	Call __builtin_exit instead of exit.
	* gcc.c-torture/compile/20000105-2.c: Add missing void types.
	* gcc.c-torture/compile/20000211-1.c (Lstream_fputc, Lstream_write)
	(Lstream_flush_out, parse_doprnt_spec): Add missing function
	declaration.
	* gcc.c-torture/compile/20000224-1.c (call_critical_lisp_code):
	Declare.
	* gcc.c-torture/compile/20000314-2.c: Add missing void types.
	* gcc.c-torture/compile/980816-1.c (XtVaCreateManagedWidget)
	(XtAddCallback): Likewise.
	* gcc.c-torture/compile/pr49474.c: Use struct
	gfc_formal_arglist * instead of (implied) int type.
	* gcc.c-torture/execute/20001111-1.c (foo): Add cast to
	char *.
	(main): Call __builtin_abort and __builtin_exit.