[foreign-memaccess+abi] RFR: 8306668: Some foreign tests fail on x86

[Maurizio Cimadamore]

Some foreign tests fail on x86, as a result of the changes in https://github.com/openjdk/panama-foreign/pull/775.
This patch reverts the `long` -> `int` conversion logic in `Utils`, and it also fixes the following:
* a new microbenchmark fails compilation on x86 because of a bad cast from pointer to long
* exclude WindowsCallArrangerTest on x86

I've tested this by building (and testing) a 32-bit JDK on my Linux x64 using `--with-target-bits=32`.

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Commit messages:
 - Fix tests and benchmarks on x86

Changes: https://git.openjdk.org/panama-foreign/pull/828/files
 Webrev: https://webrevs.openjdk.org/?repo=panama-foreign&pr=828&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306668
  Stats: 9 lines in 3 files changed: 4 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/panama-foreign/pull/828.diff
  Fetch: git fetch https://git.openjdk.org/panama-foreign.git pull/828/head:pull/828

PR: https://git.openjdk.org/panama-foreign/pull/828