[clang] [CIR][AArch64] Upstream Neon vget_lane/vgetq_lane builtins (PR #186119)

[Andrzej Warzyński via cfe-commits]

https://github.com/banach-space commented:

Thanks for the updates, I've left some fresh comments in line. 

Btw, have you considered the `dup` variants, e.g. `vdupb_lane_s8`?

https://github.com/llvm/llvm-project/pull/186119