64b76da4b6
Revert non-power-of-two vector restriction Removes the power of two restriction from rustc. As discussed in https://github.com/rust-lang/stdsimd/issues/63 r? ```@calebzulawski``` cc ```@workingjubilee``` ```@thomcc```
For high-level intro to how type checking works in rustc, see the type checking chapter of the rustc dev guide.