Wrap global variables in tree-ssa-operands.c into a class.

Wrap global variables in tree-ssa-operands.c into a class.

	* tree-ssa-operands.c (operands_scanner): New class.
	(operands_bitmap_obstack): Remove.
	(n_initialized): Remove.
	(build_uses): Move to operands_scanner class.
	(build_vuse): Same as above.
	(build_vdef): Same as above.
	(verify_ssa_operands): Same as above.
	(finalize_ssa_uses): Same as above.
	(cleanup_build_arrays): Same as above.
	(finalize_ssa_stmt_operands): Same as above.
	(start_ssa_stmt_operands): Same as above.
	(append_use): Same as above.
	(append_vdef): Same as above.
	(add_virtual_operand): Same as above.
	(add_stmt_operand): Same as above.
	(get_mem_ref_operands): Same as above.
	(get_tmr_operands): Same as above.
	(maybe_add_call_vops): Same as above.
	(get_asm_stmt_operands): Same as above.
	(get_expr_operands): Same as above.
	(parse_ssa_operands): Same as above.
	(finalize_ssa_defs): Same as above.
	(build_ssa_operands): Same as above, plus create a C-like wrapper.
	(update_stmt_operands): Create an instance of operands_scanner.