Don't crash on nested function inside cdef-func

Cython/Compiler/ParseTreeTransforms.py

@@ -2066,6 +2066,10 @@ class CreateClosureClasses(CythonTransform):
             self.path.pop()
         return node
 
+    def visit_CFuncDefNode(self, node):
+        self.visitchildren(node)
+        return node
+
 
 class GilCheck(VisitorTransform):
     """

tests/errors/e_cdef_closure.pyx

+# mode: error
+
+cdef cdef_yield():
+    def inner():
+        pass
+
+cpdef cpdef_yield():
+    def inner():
+        pass
+
+_ERRORS = u"""
+3:5: closures inside cdef functions not yet supported
+7:6: closures inside cdef functions not yet supported
+"""