RFR: 8288904: Incorrect memory ordering in UL

[Johan Sjölén]

Please review this fix for JDK-8288904, thank you.

Currently running tier1-3 tests.

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Commit messages:
 - Add memory barrier and atomic load

Changes: https://git.openjdk.org/jdk/pull/9225/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9225&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8288904
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/9225.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9225/head:pull/9225

PR: https://git.openjdk.org/jdk/pull/9225