RFR: JDK-8324682 Remove redefinition of NULL for XLC compiler [v4]

[Kim Barrett]

On Wed, 6 Mar 2024 13:02:01 GMT, Suchismith Roy <sroy at openjdk.org> wrote:

>> Remove redefinition of NULL for XLC compiler
>> In globalDefinitions_xlc.hpp there is a redefinition of NULL to work around an issue with one of the AIX headers (<dirent.h>). 
>> Once all uses of NULL in HotSpot have been replaced with nullptr, there is no longer any need for this, and it can be removed.
>> 
>> 
>> JBS ISSUE : [JDK-8324682](https://bugs.openjdk.org/browse/JDK-8324682)
>
> Suchismith Roy has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove null check

Remember to update copyrights in the changed files.

src/hotspot/share/utilities/globalDefinitions_xlc.hpp line 96:

> 94: // NULL vs NULL_WORD:
> 95: // Some platform/tool-chain combinations can't assign NULL to an integer
> 96: // type so we define NULL_WORD to use in those contexts. For xlc they are the same.

The last sentence of the comment is no longer true.

-------------

Changes requested by kbarrett (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/18064#pullrequestreview-1920715467
PR Review Comment: https://git.openjdk.org/jdk/pull/18064#discussion_r1515092953