[lworld] RFR: 8377829: [lworld] SPECjvm2008:serial performance regression in comparing JDK27 mainline and valhalla default repo default mode(without --enable-preview)

[Sergey Kuksenko]

SPECjvm2008:serial shows a performance regression when comparing JDK27 mainline and valhalla default repo default mode (without --enable-preview). The regression is -10%-15% on all platforms.
Rewriting ObjectInputStream from StreamAPI to loops and iterators allows restoring the performance.

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Commit messages:
 - 8377829: [lworld] SPECjvm2008:serial performance regression in comparing JDK27 mainline and valhalla default repo default mode(without --enable-preview)

Changes: https://git.openjdk.org/valhalla/pull/2097/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=2097&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8377829
  Stats: 19 lines in 1 file changed: 5 ins; 3 del; 11 mod
  Patch: https://git.openjdk.org/valhalla/pull/2097.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/2097/head:pull/2097

PR: https://git.openjdk.org/valhalla/pull/2097