Auto merge of #115546 - SUPERCILEX:patch-2, r=Amanieu

Weaken needlessly restrictive orderings on Arc::*_count

Follow up to rust-lang/rust#95183 from this zulip: https://rust-lang.zulipchat.com/#narrow/stream/219381-t-libs/topic/Why.20does.20Arc.3A.3Astrong_count.20use.20Acquire.20instead.20of.20Relaxed.3F/near/386213850

I'd like to use the strong_count for a lockless algorithm I'm writing, but I don't need acquire semantics so that's pointlessly restrictive on arm/risc-v.

Author: bors