RFR: 8265750: Fatal error in safepoint.cpp after backport of 8258414

[Severin Gehwolf]

On Fri, 2021-04-23 at 17:43 +0200, Jaroslav Bachorík wrote:
> Webrev: http://cr.openjdk.java.net/~jbachorik/8265750/webrev/

So this backs out JDK-8258414 and JDK-8265718 from OpenJDK 11.0.12
(jdk11u-dev only problem). Doing a backout of the two changesets
amounts to the same patch as above. Looks good.

Thanks,
Severin