DragonFly/FreeBSD: Make ss_sp *mut c_void as in the other implementations
DragonFly/FreeBSD: Make ss_sp *mut c_void as in the other implementations

This fixes compiling Rust.

cybergeek94/libc,anatol/libc,diwic/libc,cybergeek94/libc,philippkeller/libc,mneumann/libc,cactorium/libc,zethra/libc,diwic/libc,DiamondLovesYou/libc,diwic/libc,rust-lang-nursery/libc,mneumann/libc,anatol/libc,rust-lang/libc,superriva/libc,superriva/libc,zethra/libc,rust-lang/libc,zethra/libc,superriva/libc,DiamondLovesYou/libc,DiamondLovesYou/libc,philippkeller/libc,cactorium/libc,anatol/libc,DiamondLovesYou/libc,philippkeller/libc,cactorium/libc,diwic/libc,mneumann/libc,rust-lang/libc,rust-lang-nursery/libc,rust-lang-nursery/libc,cybergeek94/libc