OpenJ9 boot JDKs should be updated

[pshipton]

fyi eclipse-openj9/openj9#2519

Now that eclipse-omr/omr#2796 has been merged into OMR, we can gain some extra build performance by updating OpenJ9 boot JDKs to include that fix. It's most significant on Linux 390, but it wouldn't hurt to update all build platforms.

Suggest updating zlinux immediately to take advantage of the faster jvm, and then updating everything once the 0.9.0 release builds are available.

[pshipton]

@keithc-ca fyi

[sxa]

I need to go through a cycle of updating the boot JDKs for Java 11 anyway as part of #416 so I'll aim to do all the zLinux ones at the same time

[M-Davies]

@sxa Can this be closed?

[aahlenst]

Closing this issue due to lack of activity.

[karianna]

@sxa Can you confirm this was done?

[sxa]

It was not done - we're bootstrapping with a Hotspot VM