RFR: 8258937: Remove JVM IgnoreRewrites flag

[Harold Seigel]

Please review this change to remove the legacy JVM develop flag IgnoreRewrites.

The change was tested with Mach5 tiers 1-2 on Linux, Windows, and Mac OS, and tiers 3-5 on Linux x64.

Thanks, Harold

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Commit messages:
 - 8258937: Remove JVM IgnoreRewrites flag

Changes: https://git.openjdk.java.net/jdk/pull/1947/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1947&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8258937
  Stats: 29 lines in 2 files changed: 0 ins; 27 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1947.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1947/head:pull/1947

PR: https://git.openjdk.java.net/jdk/pull/1947