Blender Git Loki

Fix memory leak caused by node clipboard

The issue was caused by combination of following factors:

- Clipboard cleanup function will pass node tree as NULL to node free
function.

This is fine on it's own, we don't have tree in clipboard.

- Node free function will call node storage cleanup only when there is
a non-NULL node tree.

This is somewhat weird, because storage cleanup does not take node
tree as argument.

So the solution here: move node storage cleanup outside of check that
node tree is not NULL.