RFR: 8370314: Update signals_posix with new Linux signal codes [v2]

[Stefan Karlsson]

On Thu, 8 Jan 2026 12:04:34 GMT, David Holmes <dholmes at openjdk.org> wrote:

> > FWIW, @tstuefe added checks like this (minus the proposed macro) when introducing the `MAP_FIXED_NOREPLACE` define in os_linux.cpp: [3699666](https://github.com/openjdk/jdk/commit/3699666c9325b38d287e1d4d2576f8e3a662ae81)
> 
> Yes but in that case we knew the problem was that it did in fact have different values.

I don't see anything in the PR or JBS that supports this statement.

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PR Comment: https://git.openjdk.org/jdk/pull/29105#issuecomment-3723627744