[foreign-jextract] RFR: 8237585: Dismantle ForeignUnsafe

[Jorn Vernee]

These are the jextract fixes that go with https://github.com/openjdk/panama-foreign/pull/31

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Commits:
 - 5c996305: Tabs to spaces
 - 6a0154ae: Jextract fixes for ForeignUnsafe removal

Changes: https://git.openjdk.java.net/panama-foreign/pull/32/files
 Webrev: https://webrevs.openjdk.java.net/panama-foreign/32/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8237585
  Stats: 11 lines in 6 files changed: 5 ins; 2 del; 4 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/32.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/32/head:pull/32

PR: https://git.openjdk.java.net/panama-foreign/pull/32