RFR: Merge lworld [v2]

[David Simms]

> Merge jdk-16+20
> 
> Adjust to vmSymbols changes

David Simms has updated the pull request with a new target base due to a merge or a rebase. The pull request now
contains seven commits:

 - Adjust to vmSymbols changes
 - Merge branch 'lworld' into type_restrictions_merge_lworld_jdk_16_20
   
   Merge jdk-16+20
 - 8254254: [lworld][type-restrictions] Serviceability tests failing missing FIELDINFO_TAG_MASK
   
   Reviewed-by: lfoltan
 - Merge lworld
   
   Merge tag 'jdk-16+19'
 - 8254022: [lworld] [type-restrictions] Initial support for RestrictedField
   
   Reviewed-by: dsimms
 - 8253760: [type-restrictions] Static inline fields are not "erased" to the ref type
 - 8253312: Enable JVM experiments in specialization under an opt-in mode

-------------

Changes: https://git.openjdk.java.net/valhalla/pull/228/files
 Webrev: https://webrevs.openjdk.java.net/?repo=valhalla&pr=228&range=01
  Stats: 813 lines in 37 files changed: 638 ins; 103 del; 72 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/228.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/228/head:pull/228

PR: https://git.openjdk.java.net/valhalla/pull/228