Ioctl definitions

[famfo]

I am missing some ioctl definitions (defined in linux/if_tun.h in this case) or the ioctl definition macros from the libc crate to create a tap interface in Linux.

[BrandonMFong]

I made a PR for this. I looked at my if_tun.h file in my debian environment and added the macros that were missing: #3320