refactor/polish ~ fix cargo clippy complaints (allow deprecated mem::uninitialized)

.# [why]

`std::mem::MaybeUninit` is likely preffered. But `MaybeUninit` was not
stabilized until rust v1.36.0 and conversion from `mem::uninitialized` is
not obviously straight-forward at the moment.

So, 'std::mem::uninitialized' is allowed instead of increasing MinSRV to v1.36.0.

* ref: https://github.com/rust-lang/rust/blob/master/RELEASES.md

src/cp/cp.rs

@@ -739,6 +739,7 @@ fn preserve_hardlinks(
                 #[cfg(windows)]
                 {
                     let src_path: Vec<u16> = OsStr::new(source).encode_wide().collect();
+                    #[allow(deprecated)]
                     let stat = mem::uninitialized();
                     let handle = CreateFileW(
                         src_path.as_ptr(),

src/hostname/hostname.rs

@@ -46,6 +46,7 @@ pub fn uumain(args: Vec<String>) -> i32 {
     #![allow(clippy::let_and_return)]
     #[cfg(windows)]
     unsafe {
+        #[allow(deprecated)]
         let mut data = std::mem::uninitialized();
         if WSAStartup(MAKEWORD(2, 2), &mut data as *mut _) != 0 {
             eprintln!("Failed to start Winsock 2.2");

src/id/id.rs

@@ -30,7 +30,6 @@ macro_rules! cstr2cow {
 
 #[cfg(not(target_os = "linux"))]
 mod audit {
-    pub use std::mem::uninitialized;
     use super::libc::{c_int, c_uint, dev_t, pid_t, uid_t, uint64_t};
 
     pub type au_id_t = uid_t;
@@ -278,7 +277,8 @@ fn auditid() {}
 
 #[cfg(not(target_os = "linux"))]
 fn auditid() {
-    let mut auditinfo: audit::c_auditinfo_addr_t = unsafe { audit::uninitialized() };
+    #[allow(deprecated)]
+    let mut auditinfo: audit::c_auditinfo_addr_t = unsafe { std::mem::uninitialized() };
     let address = &mut auditinfo as *mut audit::c_auditinfo_addr_t;
     if unsafe { audit::getaudit(address) } < 0 {
         println!("couldn't retrieve information");

src/sync/sync.rs

@@ -72,6 +72,7 @@ mod platform {
     }
 
     unsafe fn find_first_volume() -> (String, winnt::HANDLE) {
+        #[allow(deprecated)]
         let mut name: [winnt::WCHAR; minwindef::MAX_PATH] = mem::uninitialized();
         let handle = kernel32::FindFirstVolumeW(name.as_mut_ptr(), name.len() as minwindef::DWORD);
         if handle == handleapi::INVALID_HANDLE_VALUE {
@@ -87,6 +88,7 @@ mod platform {
         let (first_volume, next_volume_handle) = find_first_volume();
         let mut volumes = vec![first_volume];
         loop {
+            #[allow(deprecated)]
             let mut name: [winnt::WCHAR; minwindef::MAX_PATH] = mem::uninitialized();
             if kernel32::FindNextVolumeW(
                 next_volume_handle,

src/unlink/unlink.rs

@@ -21,7 +21,6 @@ use getopts::Options;
 use libc::{S_IFLNK, S_IFMT, S_IFREG};
 use libc::{lstat, stat, unlink};
 use std::io::{Error, ErrorKind};
-use std::mem::uninitialized;
 use std::ffi::CString;
 
 static NAME: &str = "unlink";
@@ -71,7 +70,8 @@ pub fn uumain(args: Vec<String>) -> i32 {
     let c_string = CString::new(matches.free[0].clone()).unwrap(); // unwrap() cannot fail, the string comes from argv so it cannot contain a \0.
 
     let st_mode = {
-        let mut buf: stat = unsafe { uninitialized() };
+        #[allow(deprecated)]
+        let mut buf: stat = unsafe { std::mem::uninitialized() };
         let result = unsafe {
             lstat(
                 c_string.as_ptr(),

src/whoami/platform/windows.rs

@@ -19,6 +19,7 @@ use self::winapi::shared::lmcons;
 use self::winapi::shared::minwindef;
 
 pub unsafe fn getusername() -> Result<String> {
+    #[allow(deprecated)]
     let mut buffer: [winnt::WCHAR; lmcons::UNLEN as usize + 1] = mem::uninitialized();
     let mut len = buffer.len() as minwindef::DWORD;
     if advapi32::GetUserNameW(buffer.as_mut_ptr(), &mut len) == 0 {