[jdk17u-dev] RFR: 8279884: Use better file for cygwin source permission check

[Goetz Lindenmaier]

I backport this for parity with 17.0.16-oracle.

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Commit messages:
 - Backport 36f41cbe1126c6d9a00b21a1a68cf5f44e2f443f

Changes: https://git.openjdk.org/jdk17u-dev/pull/3306/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=3306&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8279884
  Stats: 4 lines in 1 file changed: 2 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/3306.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/3306/head:pull/3306

PR: https://git.openjdk.org/jdk17u-dev/pull/3306