RFC (XL): Merge from jdk9/jdk9

[Aleksey Shipilev]

Hi,

It has been a while since our last merge from jdk9 mainline. The last merge was
2 months ago. All repos except hotspot are pulled without a hitch. For hotspot,
there are some changes in JNIHandles that required merge. Comes with module
system update, requires jtreg b07, AdoptOpenJDK build seems to be working.

Any problems with pushing the merge?

Testing: hotspot_gc_shenandoah, jcstress -m quick

Thanks,
-Aleksey