RFR: 8360177: ParallelArguments::initialize has incorrect format string

[Kim Barrett]

Please review this trivial fix to a jio_fprintf format string. It should be using
"%zu" to print values of type uintx, rather than using "%d".

Testing: mach5 tier1
Locally tested with gcc printf warnings enabled for jio_fprintf, and verified
the warnings for the changed call are no longer present.

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Commit messages:
 - fix printing in ParallelArguments::initialize

Changes: https://git.openjdk.org/jdk/pull/25926/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25926&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8360177
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/25926.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25926/head:pull/25926

PR: https://git.openjdk.org/jdk/pull/25926