RFR(S): 8200282: Serializing non-zero byte as zero to ByteBuffer

[Roland Westrelin]

http://cr.openjdk.java.net/~roland/8200282/webrev.00/

When an arraycopy is converted to a series of loads/stores for small
copies, most of the loads use the wrong memory slice if the source and
destination are not on the same slice. That happens when EA allocated
its own slice to a non escaping allocation.

This bug is not targeted for 11 but I think it should be pushed to 11 as
it's not too risky and can lead to incorrect code execution.

Roland.