Auto merge of #616 - Arvamer:linux_input_types, r=alexcrichton

Add structs defined in linux/input.h

I was using definitions for these structs from `ioctl` but because @cmr decide to deprecate his crate (and yanked all versions :() I think that `libc` is the best place for them.

In original C header, primitive types uses aliases like `__u16` or `__s32`; for now I replaced them with Rust's counterparts but I'm not sure if it is ok, especially because tests were failing for `u64` (`unsigned long long` vs `unsigned long` on x86_64). Also, should I do something special with union in `ff_effect`?

I would like also to add all constants form `linux/input.h` and `linux/input-event-codes.h` if this PR will be accepted.