[jdk19u] RFR: 8290496: riscv: Fix build warnings-as-errors with GCC 11

Tue Sep 27 12:33:52 UTC 2022

On Mon, 26 Sep 2022 06:57:37 GMT, Feilong Jiang <fjiang at openjdk.org> wrote:

> Please review this backport to jdk19u.
> Backport of [JDK-8290496](https://bugs.openjdk.java.net/browse/JDK-8290496). Applies cleanly. Approval is pending.
> 
> Build with `--disable-warnings-as-errors` after this fix passed on unmatched board with GCC11

Got the jdk19u-fix-yes, integrate then.

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PR: https://git.openjdk.org/jdk19u/pull/40