[crac] RFR: 8358956: [CRaC] Fix NULL usage in hotspot

[Dmitry Cherepanov]

On Mon, 9 Jun 2025 09:15:03 GMT, Dmitry Cherepanov <dcherepanov at openjdk.org> wrote:

> jtreg test TestNoNULL.java fails due to a number of usages of NULL in CRaC code.
> 
> The test becomes a part of hs/tier1_common after [JDK-8352645](https://bugs.openjdk.org/browse/JDK-8352645)  (integrated in b17) and GHA starts reporting the failures after merge with jdk-25+17.
> 
> The patch replaces NULL with nullptr (and with null in comments and messages in asserts). The test passes with the change.

Thanks for the review!

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PR Comment: https://git.openjdk.org/crac/pull/237#issuecomment-2955544051