RFR: 8287122: Use gcc12 -ftrivial-auto-var-init=pattern in debug builds

[Magnus Ihse Bursie]

gcc12 has added -ftrivial-auto-var-init=<choice>, which specifies how automatic variables without an initializer should be initialized. The default choice is "uninitialized", which is the default C/C++ behavior. Alternatives are "pattern" and "zero". For improved debugging, helping to detect uninitialized uses, the "pattern" choice should be used.

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Commit messages:
 - 8287122: Use gcc12 -ftrivial-auto-var-init=pattern in debug builds

Changes: https://git.openjdk.org/jdk/pull/22587/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22587&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8287122
  Stats: 5 lines in 1 file changed: 5 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/22587.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22587/head:pull/22587

PR: https://git.openjdk.org/jdk/pull/22587