Include aio.h on DragonFly as well
Include aio.h on DragonFly as well

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