RFR: 8305093: Linker cache should not take layout names into account [v4]

[Jorn Vernee]

> Strip names from the function descriptors used in linkage requests. The names are not important for classification, and this will allow the cached MethodHandle/UpcallStubFactory to be shared across linkage request with the same structure, but with layouts that have different names.
> 
> I also have another implementation that avoids copying all the layouts, and instead re-implemented equals and hashCode in the LinkRequest wrapper: https://github.com/openjdk/jdk/compare/pr/13079...JornVernee:jdk:NoNameCache But, this seems too complex. Linking code is not very performance sensitive, so I instead went with a simpler approach in this patch.

Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:

  Use orElseGet
  
  Co-authored-by: ExE Boss <3889017+ExE-Boss at users.noreply.github.com>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13562/files
  - new: https://git.openjdk.org/jdk/pull/13562/files/a8103f67..49b8f536

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13562&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13562&range=02-03

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/13562.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13562/head:pull/13562

PR: https://git.openjdk.org/jdk/pull/13562