RFR: 8329257: AIX: Switch HOTSPOT_TOOLCHAIN_TYPE from xlc to gcc [v3]

[Kim Barrett]

On Wed, 10 Apr 2024 22:12:42 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> I can live with either, too.
>
> That build failure in shared code does not happen with Xcode clang, gcc, or
> Visual Studio, even though none of them appear to have a relevant define or
> include. So the clang variant being used for AIX is different from the Xcode
> clang variant (and maybe others) in its treatment of alloca. Weird!
> 
> I can also live with either the macro or the includes where needed.  I dislike
> conditionally adding the include in globalDefinitions_gcc.hpp.

Should also remove the `#pragma alloca` in os_aix.cpp.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/18536#discussion_r1560114722