RFR: 8303684: Lift upcall sharing mechanism to AbstractLinker (mainline) [v3]

[Jorn Vernee]

> Port of: https://github.com/openjdk/panama-foreign/pull/791 which lifts the sharing mechanism for upcall stubs to AbstractLinker.

Jorn Vernee has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains five commits:

 - Merge branch 'master' into LazyUpcalls
 - Remove spurious space
   
   Co-authored-by: Andrey Turbanov <turbanoff at gmail.com>
 - update benchmark
 - update copyright years
 - 8302346: Lift upcall sharing mechanism to AbstractLinker
   
   Reviewed-by: mcimadamore

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Changes: https://git.openjdk.org/jdk/pull/12883/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12883&range=02
  Stats: 154 lines in 16 files changed: 54 ins; 34 del; 66 mod
  Patch: https://git.openjdk.org/jdk/pull/12883.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12883/head:pull/12883

PR: https://git.openjdk.org/jdk/pull/12883