[llvm] [DataLayout] Add a specifier for element-aligned vectors (PR #180617)

[Pengcheng Wang via llvm-commits]

https://github.com/wangpc-pp commented:

IIUC, RVV is also element-aligned. @llvm/pr-subscribers-backend-risc-v 
> If an element accessed by a vector memory instruction is not naturally aligned to the size of the element, either the element is transferred successfully or an address misaligned exception is raised on that element.

By the way, can you explain the benefits if we change the vectors to element-aligned?

https://github.com/llvm/llvm-project/pull/180617