Shenandoah and 11.0.5 backports

[Aleksey Shipilev]

Hi,

Some of our Shenandoah/11 backports require changes that are backported in 11.0.5. Unfortunately,
those changes are not yet in jdk-updates/jdk11u, because the pre-release fork for 11.0.5 had not yet
started. What can we do at this point?

I see these ways out:

 a) Pull jdk-updates/jdk11u-dev (notice -dev) to sh/jdk11. This goes against our usual process of
only pulling from "stable" jdk-updates/jdk11u. The upside is that we don't have to coordinate. The
downside is we would temporarily "leak" all non-stable backports that are currently destined to
11.0.5 into our "integration repo".

 b) Cherry-pick required changes to sh/jdk11, and then wait for the final merge to render the
difference against upstream nil. The upside is that we are completely isolated from upstream
processes. The downside is that we would have double changesets after all this is done, and also we
would temporarily "leak" some backports from 11.0.5 into our "integration repo".

 c) Ask 11u updates project to tag 11.0.5+1 and push it to jdk-updates/jdk11u, then we pick it up
via the regular channel. The upside is that this path would not be exceptional. The downside is that
we would need to coordinate such a push in upstream.

I am leaning towards (a), then (b), then (c). Opinions?
	
-- 
Thanks,
-Aleksey