RFR 8153310: AArch64: JEP 254: Implement byte_array_inflate and char_array_compress

[Andrew Haley]

We need this for CompactStrings.

http://cr.openjdk.java.net/~aph/8153310/

https://bugs.openjdk.java.net/browse/JDK-8153310

Note: this depends on http://cr.openjdk.java.net/~aph/8152554/
which is still pending review.

Thanks,

Andrew.