RFR: 8303810: Move attribute of FileMapInfo::fail_stop to match JDK-8302124

[Julian Waters]

Cleanup of [JDK-8292269](https://bugs.openjdk.org/browse/JDK-8292269) to move an attribute missed in it to match the HotSpot Style Guide's required attribute position

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Commit messages:
 - 8303810: Move attribute of FileMapInfo::fail_stop to match JDK-8302124

Changes: https://git.openjdk.org/jdk/pull/12918/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12918&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303810
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/12918.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12918/head:pull/12918

PR: https://git.openjdk.org/jdk/pull/12918