RFR: JDK-8266892: avoid maybe-uninitialized gcc warnings on linux s390x

[Matthias Baesken]

In the linux s390x hs code there are a few "maybe-uninitialized" gcc warnings with gcc 8 (those warning class is disabled currently in jdk17 but enabled e.g. in jdk11).  It would be good to fix them anyway which is done by this small change.

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Commit messages:
 - JDK-8266892

Changes: https://git.openjdk.java.net/jdk/pull/3970/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3970&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8266892
  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3970.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3970/head:pull/3970

PR: https://git.openjdk.java.net/jdk/pull/3970