RFR (sh/jdk8): Bulk backports sh/jdk11 -> sh/jdk8

[Roman Kennke]

>> JDK-8223184: Shenandoah: Missing roots in SRP::process_all_roots_slow
> 
> I suspect this one is not applicable to 8u. JNIHandles::weak_oops_do walks
> JvmtiExport::weak_oops_do, is it not?
> 
> Similar thing caused us headache before:
>   https://bugs.openjdk.java.net/browse/JDK-8223258

Right! Good spot! I actually had JDK-8223258 on my backports list but
then cut it out. Gaa, jdk8 roots stuff is such a mess. Well, I guess we
can cut both out and be happy.


>> Changesets:
>> http://cr.openjdk.java.net/~rkennke/backport-shjdk8-2020-02-27/changesets.txt
>> Webrev:
>> http://cr.openjdk.java.net/~rkennke/backport-shjdk8-2020-02-27/webrev.00/
> 
> Otherwise looks good.

Will push without the weakroots change.

Thank you,
Roman