RFR: Add support for bin folder in makefile

Mon May 27 14:20:38 UTC 2024

A previous PR changed the gradle build to emit launcher scripts in a separate "bin" folder. However, that PR did not make any changes to the makefiles used to produce the binary bundles. This PR rectifies that.

Tested locally.

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Commit messages:
 - Initial push

Changes: https://git.openjdk.org/jextract/pull/247/files
  Webrev: https://webrevs.openjdk.org/?repo=jextract&pr=247&range=00
  Stats: 3 lines in 1 file changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jextract/pull/247.diff
  Fetch: git fetch https://git.openjdk.org/jextract.git pull/247/head:pull/247

PR: https://git.openjdk.org/jextract/pull/247