RFC: Pick up jdk-11.0.5+5 to sh/jdk11

[Aleksey Shipilev]

Let's pick up jdk-11.0.5+5 to sh/jdk11.

The merge is not trivial in aarch64 parts, because this change landed:
  8209420: Track membars for volatile accesses so they can be properly optimized

It conflicts with changes in aarch64.ad and compile.cpp. I merged them by ditching changes in
"leading_to_normal" we have in aarch64.ad [1] and adding a few new cases in compile.cpp. We would
need to see what testing says about the success of that merge.

Full change list:
  https://cr.openjdk.java.net/~shade/shenandoah/merges/jdk11-11.0.5%2b5/changesets.txt

Testing: x86_64 hotspot_gc_shenandoah; aarch64 cross-build

-- 
Thanks,
-Aleksey

[1]
https://builds.shipilev.net/patch-openjdk-shenandoah-jdk11/src/hotspot/cpu/aarch64/aarch64.ad.sdiff.html