RFR(S) 8231756: [JVMCI] need support for deoptimizing virtual byte arrays encoding non-byte primitives

[Tom Rodriguez]

http://cr.openjdk.java.net/~never/8231756/webrev
https://bugs.openjdk.java.net/browse/JDK-8231756

This adds support for deoptimizing with non-byte primitive values stored 
on top of a byte array, similarly to the way that a double or long can 
be stored on top of 2 int fields.  More detail is provided in the bug 
report and new unit tests exercise the deoptimization.  mach5 testing is 
in progress.

tom