func cmsgAlignOf(salen int) int {
	salign := SizeofPtr
	if darwin64Bit || dragonfly64Bit || solaris64Bit {
		salign = 4
	}
	return (salen + salign - 1) & ^(salign - 1)
}
Round the length of a raw sockaddr up to align it properly.
package unix
import "unsafe"