Integrated: 7903349: int parameter in generated allocateArray method should be long

[Athijegannathan Sundararajan]

Changing "int" param to "long" in generated allocateArray method for struct classes.

Piggybacking couple of code review suggestions missed during review for CODETOOLS-7903257

-------------

Commit messages:
 - 7903349: int parameter in generated allocateArray method should be long

Changes: https://git.openjdk.org/jextract/pull/86/files
 Webrev: https://webrevs.openjdk.org/?repo=jextract&pr=86&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903349
  Stats: 8 lines in 2 files changed: 4 ins; 1 del; 3 mod
  Patch: https://git.openjdk.org/jextract/pull/86.diff
  Fetch: git fetch https://git.openjdk.org/jextract pull/86/head:pull/86

PR: https://git.openjdk.org/jextract/pull/86