RFR: 8170106: AArch64: Multiple JVMCI issues

[Andrew Haley]

JVMCI nearly works, but there are multiple minor bugs which make it
non-functional.  It's not possible to separate these into multiple
issues, so this is a composite patch.

The handling of some relocs is wrong.
Narrow klasses and OOPs have only partial support, returning Unimplemented()
Register numbering for float registers is wrong
Scratch registers r8 and r9 aren't marked as non-allocatable.

http://cr.openjdk.java.net/~aph/8170106

Andrew.