zdtm.py: don't worry if a test class doesn't have ns() and static()

Signed-off-by: Andrew Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm.py

@@ -766,7 +766,8 @@ def get_visible_state(test):
 	files	= {}
 	mounts	= {}
 
-	if not test.static() or not test.ns():
+	if not getattr(test, "static", lambda : False)() or \
+	   not getattr(test, "ns", lambda : False)():
 		return ({}, {}, {})
 
 	r = re.compile('^[0-9]+$')