Function core::ptr::swap_nonoverlapping_simple_untyped

unsafe fn swap_nonoverlapping_simple_untyped<T>(
    x: *mut T,
    y: *mut T,
    count: usize
)

Same behaviour and safety conditions as swap_nonoverlapping

LLVM can vectorize this (at least it can for the power-of-two-sized types swap_nonoverlapping tries to use) so no need to manually SIMD it.