Copy length items to dest starting from dest.

Property definitions

core $ NativeArray :: memmove
	# Copy `length` items to `dest` starting from `dest`.
	fun memmove(start: Int, length: Int, dest: NativeArray[E], dest_start: Int) is intern do
		if start < dest_start then
			var i = length
			while i > 0 do
				i -= 1
				dest[dest_start+i] = self[start+i]
			end
		else
			var i = 0
			while i < length do
				dest[dest_start+i] = self[start+i]
				i += 1
			end
		end
	end
lib/core/collection/array.nit:997,2--1012,4