Fix xmethod Python so that it works with Python3.

Fix xmethod Python so that it works with Python3.

gdb/

	* python/lib/gdb/command/xmethods.py (set_xm_status1): Use the
	'items'	methods instead of 'iteritems' method on dictionaries.

gdb/testsuite/

	* gdb.python/py-xmethods.py (A_getarrayind)
	(E_method_char_worker.__call__, E_method_int_worker.__call__):
	Use 'print' with function call syntax.
	(E_method_matcher.match): Fix tab vs space indentation mixup.