add truncate64 on linux
add truncate64 on linux

rust-lang/libc,rust-lang-nursery/libc,cactorium/libc,cactorium/libc,anatol/libc,rust-lang/libc,anatol/libc,rust-lang-nursery/libc,rust-lang/libc,mneumann/libc,mneumann/libc,cactorium/libc,mneumann/libc,anatol/libc,rust-lang-nursery/libc