RFR: 8302790: Set FileMapRegion::mapped_base() to null if mapping fails

Wed Nov 29 17:57:26 UTC 2023

For cleanliness, we should reset FileMapRegion::mapped_base() to nullptr in case the mapping fails for any reasons. This patch moves the `set_mapped_base()` call after all the checks complete so it can remain as null in case checks fail. Verified with tier 1-5 tests.

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Commit messages:
 - Moved assignment after checks
 - 8302790: Set FileMapRegion::mapped_base() to null if mapping fails

Changes: https://git.openjdk.org/jdk/pull/16866/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16866&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8302790
  Stats: 20 lines in 2 files changed: 7 ins; 5 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/16866.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16866/head:pull/16866

PR: https://git.openjdk.org/jdk/pull/16866