RFR: 8314488: Compile the JDK as C++17 [v2]

[Kim Barrett]

On Fri, 15 Dec 2023 08:12:47 GMT, Julian Waters <jwaters at openjdk.org> wrote:

>> No problem!
>
> There are, strangely, many more register keywords in the JDK codebase than just this one, but none of them throw the same errors, only this one does

Looks like this change has also already been made, by JDK-8319440.

All of the other non-comment uses of "register" I found in HotSpot are gcc local variable register specifications:
https://gcc.gnu.org/onlinedocs/gcc-13.2.0/gcc/Local-Register-Variables.html
So are a different thing and not affected by the deprecation/removal of the C++ "register" keyword.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/14988#discussion_r1427728697