RFR: 8295964: Move InstanceKlass::_misc_flags

[Coleen Phillimore]

I moved misc_flags out to their own misc flags class so that we can put the writeable accessFlags there too with atomic access.

Tested with tier1-4.

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Commit messages:
 - 8295964: Move InstanceKlass::_misc_flags

Changes: https://git.openjdk.org/jdk/pull/10249/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10249&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8295964
  Stats: 352 lines in 9 files changed: 156 ins; 160 del; 36 mod
  Patch: https://git.openjdk.org/jdk/pull/10249.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10249/head:pull/10249

PR: https://git.openjdk.org/jdk/pull/10249