RFR: 8255992: JFR EventWriter does not use first string from StringPool with id 0 [v2]

[Jie Kang]

> This allows string pool entry with id 0 to be written in short form for the event data.

Jie Kang has updated the pull request incrementally with one additional commit since the last revision:

  Compare against zero instead of negative one

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1097/files
  - new: https://git.openjdk.java.net/jdk/pull/1097/files/7f063a6a..45c5088c

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1097&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1097&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1097.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1097/head:pull/1097

PR: https://git.openjdk.java.net/jdk/pull/1097