[jdk11u-dev] RFR: 8281275: Upgrading from 8 to 11 no longer accepts '/' as filepath separator in gc paths

[Goetz Lindenmaier]

I backport this for parity with 11.0.16-oracle.

I had to resolve the copyrights, the rest applied clean. Marking as clean backport.

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Commit messages:
 - Backport 84868e39be4522ba87e603beea0f8da9efa43b6d

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/935/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=935&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8281275
  Stats: 28 lines in 2 files changed: 23 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/935.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/935/head:pull/935

PR: https://git.openjdk.java.net/jdk11u-dev/pull/935