RFR: 8316645: RISC-V: Remove dependency on libatomic by adding cmpxchg 1b

[Robbin Ehn]

On Fri, 29 Sep 2023 16:27:48 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> Hi all, please consider.
>> 
>> latomic is used for non native atomic operation which causes problems with extra dependency.
>> This have been fixed in recent gcc, so latomic is no longer needed.
>> 
>> Added new gtest, passes t1 on vf2/qemu.
>
> Nice!

@Hamlin-Li thanks!

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PR Comment: https://git.openjdk.org/jdk/pull/15919#issuecomment-1742131713