RFR: 8306882: (fs) Path.toRealPath(LinkOption.NOFOLLOW_LINKS) fails when "../../" follows a link

[Brian Burkhalter]

Modify `Path.toRealPath` such that it does not collapse links such as "link/.." or "link/../.." when `LinkOption.NOFOLLOW_LINKS` is specified or, in some cases, not.

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

Commit messages:
 - 8306882: (fs) Path.toRealPath(LinkOption.NOFOLLOW_LINKS) fails when "../../" follows a link

Changes: https://git.openjdk.org/jdk/pull/15397/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15397&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306882
  Stats: 175 lines in 3 files changed: 131 ins; 1 del; 43 mod
  Patch: https://git.openjdk.org/jdk/pull/15397.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15397/head:pull/15397

PR: https://git.openjdk.org/jdk/pull/15397