RFR: 8253031: git jcheck complains about invalid tags in jdk repo after fix for JDK-8252844

[Kevin Rushforth]

In the fix for [JDK-8252844](https://bugs.openjdk.java.net/browse/JDK-8252844) the tags entry in `.jcheck/conf` was
copied from the Skara Java code. The `` chars were escaped as `\` in the Java String so that it would contain ``. This
additional level of escape is not needed in the `.jcheck/conf` file, and causes the regex to not be as intended. The
fix is to replace `\` with `/` in the regex.

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Commit messages:
 - 8253031: git jcheck complains about invalid tags in jdk repo after fix for JDK-8252844

Changes: https://git.openjdk.java.net/jdk/pull/131/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=131&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8253031
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/131.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/131/head:pull/131

PR: https://git.openjdk.java.net/jdk/pull/131