eo: Allow efl_reuse to be called with a parent

eo: Allow efl_reuse to be called with a parent

If an object still has a parent inside the del intercept, we shouldn't
reset the "parent_sunk" flag. This would indeed break logic as
parent_sunk == false implies that a parent was never set, which means
the parent must be null. Right now this case isn't used but it can be
imagined with caches of evas objects (they should remain parented to
their evas).

@fix