use :: to disambiguate use

Without this, rustc 1.48 (as of now, rustc nightly-2020-10-04) is
expected to fail to build rust-systemd.

Rustc issue: rust-lang/rust#77586

Author: codyps

src/daemon.rs

@@ -5,7 +5,7 @@
 use super::ffi::{c_int, pid_t, size_t};
 use super::{Error, Result};
 use cstr_argument::CStrArgument;
-use ffi::daemon as ffi;
+use ::ffi::daemon as ffi;
 use libc::{c_char, c_uint};
 use libc::{SOCK_DGRAM, SOCK_RAW, SOCK_STREAM};
 use std::io::ErrorKind;

src/login.rs

@@ -1,7 +1,7 @@
 use super::ffi::{c_char, c_uint, pid_t, uid_t};
 use super::{free_cstring, Result};
 use cstr_argument::CStrArgument;
-use ffi::login as ffi;
+use ::ffi::login as ffi;
 use std::ptr;
 
 /// Systemd slice and unit types