[lworld] Integrated: 8342036: [lworld] tools/javap/UndefinedAccessFlagTest.java fails after merge of jdk-24+4

[Vicente Romero]

fixing `com.sun.tools.javap.ClassWriter::getClassModifiers` to use method `flagsReportUnknown` which capture exceptions thrown by `AccessFlag.maskToAccessFlags`

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Commit messages:
 - 8342036: [lworld] tools/javap/UndefinedAccessFlagTest.java fails after merge of jdk-24+4

Changes: https://git.openjdk.org/valhalla/pull/1310/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1310&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8342036
  Stats: 8 lines in 3 files changed: 0 ins; 1 del; 7 mod
  Patch: https://git.openjdk.org/valhalla/pull/1310.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1310/head:pull/1310

PR: https://git.openjdk.org/valhalla/pull/1310