RFR: 8333236: Test java/foreign/TestAccessModes.java is timing out after passing

[Maurizio Cimadamore]

This PR restores a var handle cache in `Utils::makeSegmentViewVarHandle`. The cache was moved to `ValueLayouts::varHandle` as part of [pull/19251](https://git.openjdk.org/jdk/pull/19251), on the basis that we want to optimize the common case like:


ValueLayout layout = ...
layout.varHandle().get(...)


And that caching more complex var handles didn't seem to add value, given that, for these var handles, the logic in `LayoutPath` needs to adapt the returned var handle anyways.

But, `TestAccessModes` revealed a different picture - w/o any cache in `Utils` the test end up allocating 8963 var handle instances (instead of just 4), in each of the 4 runs the test includes. While this is admittedly a stress test, it seems nice to restore the level of sharing we had before [pull/19251](https://git.openjdk.org/jdk/pull/19251).

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Commit messages:
 - Initial push

Changes: https://git.openjdk.org/jdk/pull/19485/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19485&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8333236
  Stats: 11 lines in 1 file changed: 10 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/19485.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19485/head:pull/19485

PR: https://git.openjdk.org/jdk/pull/19485