WT-8959 looked at the x86 and ARM64 platforms to ensure that the atomic primitives provided sufficient memory barriers as needed by WiredTiger. WiredTiger expects a full memory barrier, which is bidirectional for all memory accesses and not just the memory location the primitive operates on.

We also need to confirm the same for PowerPC; it is suspected that atomic increment doesn't necessarily provide the memory barrier guarantees that we need. Depending upon the appetite this ticket can be generalised across a larger set of atomic primitives and more platforms.