RFC: linux-aarch64 and LSE support

[Kim Barrett]

> On Sep 14, 2022, at 5:30 AM, Andrew Haley <aph-open at littlepinkcloud.com> wrote:
> 
> On 9/14/22 10:25, Andrew Dinn wrote:
>> I am swayed by Kim's arguments that we should clean this up now. This is
>> technical debt and the changes Kim wants to make imply an interest rate
>> hike (extra development and maintenance).
> 
> OK, thanks. It seems to me to be more balanced: the current version has
> (slightly) better performance and is more configurable, but I take your
> point about maintenance.

OK, I'll file a JBS issue and put together a PR to make this switch.

I *think* it can be done as a sequence of commits to revert prior commits,
followed by a couple of newly developed commits to reinstate features like
support for relaxed atomics.