RFR: 8346847: [s390x] minimal build failure

[Amit Kumar]

On Fri, 27 Dec 2024 06:32:49 GMT, Amit Kumar <amitkumar at openjdk.org> wrote:

> While working on [JDK-8343884](https://bugs.openjdk.org/browse/JDK-8343884), I made sure that `OptoScheduling` remains disabled on s390x, but for that code was not guarded by C2-specific if-def (`COMPILER2`) . Which caused a build failure on minimal-vm (see JBS issue for log). This is trivial fix for that.

GHA failure for mac/x64 is not related to this change.

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PR Comment: https://git.openjdk.org/jdk/pull/22887#issuecomment-2563533455