Handle TCSETSW and TCSETSF in ioctl

Fixes #168 (closed).

I noticed that dup_{read,write} might have some UB, so I added a TODO comment about it. I think to fix that todo, there would have to be changes across here, redox-syscall, and the kernel to pass around pointers rather than references, but I figure you gotta start somewhere.

src/header/sys_ioctl/redox.rs

@@ -84,7 +84,7 @@ pub unsafe extern "C" fn ioctl(fd: c_int, request: c_ulong, out: *mut c_void) ->
             }
         }
         // TODO: give these different behaviors
-        TCSETS..=TCSETSF => {
+        TCSETS | TCSETSW | TCSETSF => {
             let termios = &*(out as *const termios::termios);
             if e(dup_write(fd, "termios", termios)) == !0 {
                 -1