[lworld] RFR: 8348607: [lworld] Calls to Unsafe.getValue() / Unsafe.putValue() must be updated

[Chen Liang]

Core libraries counterpart of #1336.

This requires MemberName to fetch more information in initialization. A new int high flag field is added, in anticipation to a merger with the regular int flag field in the future. Currently, directly migrating the flags field to long is too impactful to the whole codebase.

Also 8348680 is addressed as well; it's some minor updates to make the null checks specific to references VH.

Testing: test/jdk/java/lang/invoke

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Commit messages:
 - Remove redundant checks for missing locations
 - New field in MemberName for now
 - Adapt layouts stage 1 (need to store in MemberName)

Changes: https://git.openjdk.org/valhalla/pull/1340/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1340&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8348607
  Stats: 234 lines in 13 files changed: 63 ins; 0 del; 171 mod
  Patch: https://git.openjdk.org/valhalla/pull/1340.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1340/head:pull/1340

PR: https://git.openjdk.org/valhalla/pull/1340