[jdk21u-dev] RFR: 8329961: Buffer overflow in os::Linux::kernel_version

[Severin Gehwolf]

Follow-up fix to [JDK-8321075](https://bugs.openjdk.org/browse/JDK-8321075) which is in 21.0.4. Should be low risk and avoids the potential buffer-overrun.

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Commit messages:
 - Backport 279ed0ddd505fb3052b818f755b4b220ed5557e6

Changes: https://git.openjdk.org/jdk21u-dev/pull/498/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=498&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8329961
  Stats: 10 lines in 1 file changed: 0 ins; 7 del; 3 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/498.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/498/head:pull/498

PR: https://git.openjdk.org/jdk21u-dev/pull/498