Allow vector types for amdgpu
The amdgpu target uses vector types in various places. The vector types can be used on all architectures, there is no associated target feature that needs to be enabled.
The largest vector type found in LLVM intrinsics is `v32i32` (`[32 x i32]`) for mfma intrinsics. Note that while this intrinsic is only supported on some architectures, the vector type itself is supported on all architectures.
Tracking issue: rust-lang/rust#135024
(I used an empty string to say “does not need a target feature”. If you prefer an `Option` or something like that, I’ll change it.)
3e412faa66