[jdk11u-dev] RFR: 8261445: Use memory_order_relaxed for os::random().

[Victor Rudometov]

Backport https://bugs.openjdk.org/browse/JDK-8261445 Use memory_order_relaxed for os::random() for jdk11u

Backport not clean, however the change is trivial.
Tested in linux x64/aarch64: tier1, tier2, jck's passed.

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Commit messages:
 - Backport a25bae823979fc96d01a2e349506ed3b1ea39762

Changes: https://git.openjdk.org/jdk11u-dev/pull/1480/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1480&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8261445
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1480.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev pull/1480/head:pull/1480

PR: https://git.openjdk.org/jdk11u-dev/pull/1480