RFR: 8305771: SA ClassWriter.java fails to skip overpass methods

[Ioi Lam]

Please review this trivial fix.

When checking for bits in `m.getAccessFlags()`, the mask `JVM_RECOGNIZED_METHOD_MODIFIERS` should be applied (similar to other uses of `m.getAccessFlags()` in ClassWriter.java

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Commit messages:
 - 8305771: SA ClassWriter.java fails to skip overpass methods

Changes: https://git.openjdk.org/jdk/pull/13663/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13663&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8305771
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/13663.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13663/head:pull/13663

PR: https://git.openjdk.org/jdk/pull/13663