RFR: 8270179: Rename Amalloc_4 [v4]

[Thomas Stuefe]

On Mon, 12 Jul 2021 23:56:21 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> This renames Amalloc_4 to AmallocWords.  While I had to fix internal_malloc_4, which is a copy of Amalloc_4 (except with UseMallocOnly handling), I also made the change for
>> JDK-8270217 Fix Arena::Amalloc to check for overflow better
>> Tested with tier1 - all Oracle platforms and tier1-3 on linux-x64.
>
> Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Rename internal_malloc_only to internal_amalloc, which is a better name.

LGTM (besides the alignment issue as well as the somewhat unclear comments, but both can be fixed with the follow-up RFE)

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Marked as reviewed by stuefe (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/4750