This reverts commit e22a64e8d8d4da46c74f878ce1c23ad1c88982e8.
This caused a regression such that types like `[[u8; 256]; 4]`
no longer implemented Clone. This previously worked due to Clone
for `[T; N]` (N in 0 to 32) being implemented for T: Copy.
Due to fixed size arrays not implementing Clone for sizes above 32,
the new implementation requiring T: Clone would not allow
`[[u8; 256]; 4]` to be Clone.
0a9c463195