RFR: 7903763: [jtreg] grep: /proc/version: No such file or directory [v2]

[SendaoYan]

> Hi all,
> In rpmbuild mock enviroment, there is not `/proc/version` file, `jtreg -version` command will print `grep: /proc/version: No such file or directory` message.
> This PR add check the file `/proc/version` exists or not before execute command `grep /proc/version`
> The change has been verified locally, no risk.

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

  modify the copyright year to 2024

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

Changes:
  - all: https://git.openjdk.org/jtreg/pull/210/files
  - new: https://git.openjdk.org/jtreg/pull/210/files/fcfd90b7..07d75684

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jtreg&pr=210&range=01
 - incr: https://webrevs.openjdk.org/?repo=jtreg&pr=210&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jtreg/pull/210.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/210/head:pull/210

PR: https://git.openjdk.org/jtreg/pull/210