RFR: 8355570: [s390x] Update -march to z13 generation

[Amit Kumar]

updated march level from z10 to z13.

Testing: tier1 (fastdebug-vm)

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Commit messages:
 - z10 -> z15

Changes: https://git.openjdk.org/jdk/pull/24869/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24869&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8355570
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/24869.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24869/head:pull/24869

PR: https://git.openjdk.org/jdk/pull/24869