667 has an initializer like `a = b = new X()`. This broke the previous
version of the unscrambler, as it treated it as two separate
initializers: `a = b = new X()` and `b = new X()`. When the fields were
moved, the overlapping instructions were removed twice from the original
<clinit> method, making its size negative.
Even if this were fixed, it is still not safe to move the initializers,
as `new X()` would end up being executed twice, not once.
This commit fixes the problem by treating any simple initializer that
overlaps with any other simple initializer as a complex initializer.
Signed-off-by: Graham <gpe@openrs2.org>