RFR: 8360281: VMError::error_string has incorrect format usage

[Kim Barrett]

Please review this trivial change to VMError::error_string, applying the `p2i`
helper function to a pointer being used as the value for a PTR_FORMAT directive.

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

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Commit messages:
 - fix printing in VMError::error_string

Changes: https://git.openjdk.org/jdk/pull/25935/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25935&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8360281
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/25935.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25935/head:pull/25935

PR: https://git.openjdk.org/jdk/pull/25935