RFR: 8254265: s390 and linux 32 bit builds broken

[Martin Doerr]

JDK-8253717 missed 2 ocurrances of JavaThread::stack_guard_zone_size() which was moved to class StackOverflow.

I just verified s390 build. Can anybody check linux 32 bit?

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Commit messages:
 - 8254265: s390 and linux 32 bit builds broken

Changes: https://git.openjdk.java.net/jdk/pull/568/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=568&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8254265
  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/568.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/568/head:pull/568

PR: https://git.openjdk.java.net/jdk/pull/568