RFR: 8269760: idea.sh should not invoke cygpath directly [v2]

[Jorn Vernee]

> From the JBS issue:
> 
> Currently idea.sh checks if `CYGPATH` is set, and then continues by invoking `cygpath` directly.
> 
> This doesn't work if `CYGPATH` is not actually set to `cygpath`, but to something else, such as `wslpath`.
> 
> Instead of invoking `cygpath` directly, the value of the `CYGPATH` variable should be used.

Jorn Vernee has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4655/files
  - new: https://git.openjdk.java.net/jdk/pull/4655/files/a95d4154..a95d4154

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4655&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4655&range=00-01

  Stats: 0 lines in 0 files changed: 0 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4655.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4655/head:pull/4655

PR: https://git.openjdk.java.net/jdk/pull/4655