Change cypclass lock transform to only lock around attribute accesses

Cython/Compiler/ExprNodes.py

@@ -7295,6 +7295,7 @@ class AttributeNode(ExprNode):
         return node
 
     def analyse_types(self, env, target = 0):
+        self.is_target = target
         self.initialized_check = env.directives['initializedcheck']
         node = self.analyse_as_cimported_attribute_node(env, target)
         if node is None and not target:

Cython/Compiler/Nodes.py

@@ -8597,6 +8597,9 @@ class LockCypclassNode(StatNode):
 
     child_attrs = ["body", "obj"]
 
+    nested = False
+    objs = None
+
     def analyse_declarations(self, env):
         self.body.analyse_declarations(env)
         self.obj.analyse_declarations(env)