RFR: 8374945: Avoid fstat in os::open

[Jonas Norlinder]

Eliminate unnecessary calls to fstat in os::open akin to JDK-8373647. This optimization reduces system overhead.

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Commit messages:
 - Remove trailing whitespace
 - [Linux] Avoid fstat in os::open

Changes: https://git.openjdk.org/jdk/pull/29152/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29152&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8374945
  Stats: 5 lines in 1 file changed: 4 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/29152.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29152/head:pull/29152

PR: https://git.openjdk.org/jdk/pull/29152