Related to #813.

Depends on #2310.

In #2434, we found that vectorized find and count don't build for ARM64EC due to missing intrinsics. The existing attempt to enable reverse and reverse_copy for ARM64EC was also questionable, as @cbezault found a broken SSE intrinsic. I'm going to disable the vectorized algorithms for ARM64EC, so this issue is for followup investigation.

• Can we get the broken SSE intrinsic fixed, so we can re-enable reverse and reverse_copy for ARM64EC?
• Should ARM64 NEON algorithms (Extend vectorized algorithms to ARM64/ARM64EC #813) supersede any attempt to get SSE codepaths working for ARM64EC?