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

[Jaroslav Bachorík]

Please, review this backout patch for a backport causing fatal error.

JIRA: https://bugs.openjdk.java.net/browse/JDK-8265750
Webrev: http://cr.openjdk.java.net/~jbachorik/8265750/webrev/

The backout changes also revert the change introduced by
https://bugs.openjdk.java.net/browse/JDK-8265718 as the affected code
is not present any more.

Tier 1 tests are passing on linux x64 but I have no windows machine
ready for JDK build and tests (as was obvious from the breakage ...).
So, if someone could do a test run on windows x64 (at least) I would
greatly appreciate it.

Thanks,

-JB-