[aarch64-port-dev ] AArch64 process

[Andrew Haley]

I managed to confuse myself completely by checking some patches into JDK8
and some into JDK9.  I think it's straightened out now.

I think we need a rule, so here it is: all patches that are not JDK9
specific should go into JDK8 then JDK9.  As before, no changes to shared
code are allowed into JDK9 except under special circumstances.

JDK7u should use the same HotSpot as JDK8.

Andrew.