stage2: fix @sizeOf() for vector types.

[xxxbxxx]

stage1 does

        entry->abi_size = LLVMABISizeOfType(g->target_data_ref, example_vector_llvm_type);
        entry->abi_align = LLVMABIAlignmentOfType(g->target_data_ref, example_vector_llvm_type);

but looks like it's actually pretty direct, same as alignment. (next power-of-2)
maybe some architectures are different?

follow-up of 095e24e

closes #12026

[andrewrk]

Thanks for the patch!

Note that this changed in LLVM 14. Here is the corresponding alignment patch: b698168

[xxxbxxx]

not smart enough to get the tests to pass both on llvm13 and llvm14 -> rebasing on llvm14 branch..

[xxxbxxx]

done better by a37cd0b from #12145.