RFR: 8313552: Fix -Wconversion warnings in JFR code [v4]

[Markus Grönlund]

> Greetings,
> 
> this change set removes -Wconversion warnings in the JFR code.
> 
> Testing: jdk_jfr
> 
> Thanks
> Markus

Markus Grönlund has updated the pull request incrementally with one additional commit since the last revision:

  revert to static_cast

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15152/files
  - new: https://git.openjdk.org/jdk/pull/15152/files/9fa7a46e..11d4953f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15152&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15152&range=02-03

  Stats: 49 lines in 7 files changed: 0 ins; 0 del; 49 mod
  Patch: https://git.openjdk.org/jdk/pull/15152.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15152/head:pull/15152

PR: https://git.openjdk.org/jdk/pull/15152