RFR: 7903626: Add struct helper method to reintrepret an array of structs [v2]

[Jorn Vernee]

> This patch renames the existing `ofAddress` method we generate in struct classes to `reinterpret` to reflect the latest naming changes in the FFM API. It also adds another overload that takes an element count, for reinterpreting arrays. Finally, this patch adds the missing cleanup parameter that the underlying reinterpret method accepts.

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

  call array overload of reinterpret from scalar overload

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Changes:
  - all: https://git.openjdk.org/jextract/pull/178/files
  - new: https://git.openjdk.org/jextract/pull/178/files/196c3b4b..e9678b4d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jextract&pr=178&range=01
 - incr: https://webrevs.openjdk.org/?repo=jextract&pr=178&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jextract/pull/178.diff
  Fetch: git fetch https://git.openjdk.org/jextract.git pull/178/head:pull/178

PR: https://git.openjdk.org/jextract/pull/178