Update to Rust 1.39.0

Summary:
Release notes: https://github.com/rust-lang/rust/blob/stable/RELEASES.md#version-1390-2019-11-07
Dist: https://dev-static.rust-lang.org/dist/2019-11-04/index.html

This diff includes fixes for new warnings inside of targets that set deny(warnings). I will fix any other new warnings in a separate diff to keep this one as small as possible.

- feature(bind_by_move_pattern_guards) has been stabilized
- feature(async_await) has been stabilized
- new warning on duplicate semicolon typos;;
- deprecation of std::mem::uninitialized in favor of MaybeUninit
- adjustment to how locals are captured in non-move async blocks
- soundness fix to disallow Send of fmt::Arguments

Reviewed By: jsgf

Differential Revision: D18358129

fbshipit-source-id: 718b6b7f3e35bf0f3d7098a07739191c862ac82d

apiserver/src/main.rs

@@ -6,7 +6,6 @@
  * directory of this source tree.
  */
 
-#![feature(async_await)]
 #![deny(warnings)]
 
 use std::sync::Arc;

blobstore/cacheblob/src/memcache_cache_lease.rs

@@ -283,7 +283,7 @@ impl LeaseOps for MemcacheOps {
 
     fn release_lease(&self, key: &str, put_success: bool) -> BoxFuture<(), ()> {
         let mc_key = self.presence_keygen.key(key);
-        LEASE_STATS::release.add_value(1, (self.lease_type,));;
+        LEASE_STATS::release.add_value(1, (self.lease_type,));
         if put_success {
             let uploaded = compact_protocol::serialize(&LockState::uploaded_key(key.to_string()));
             LEASE_STATS::release_good.add_value(1, (self.lease_type,));

cmdlib/src/lib.rs

@@ -9,7 +9,7 @@
 //! Scaffolding that's generally useful to build CLI tools on top of Mononoke.
 
 #![deny(warnings)]
-#![feature(never_type, bind_by_move_pattern_guards)]
+#![feature(never_type)]
 
 pub mod args;
 pub mod helpers;

cmds/admin/main.rs

@@ -7,7 +7,6 @@
  */
 
 #![deny(warnings)]
-#![feature(async_await)]
 #![feature(process_exitcode_placeholder)]
 
 use clap::{App, Arg, SubCommand};

lfs_server/src/main.rs

@@ -7,7 +7,7 @@
  */
 
 #![recursion_limit = "256"]
-#![feature(async_await, async_closure, option_flattening, never_type)]
+#![feature(async_closure, option_flattening, never_type)]
 #![deny(warnings)]
 
 use clap::Arg;

mononoke_api/src/lib.rs

@@ -7,7 +7,6 @@
  */
 
 #![deny(warnings)]
-#![feature(async_await)]
 
 use std::collections::HashMap;
 use std::sync::Arc;

pushrebase/src/lib.rs

@@ -8,7 +8,6 @@
 
 #![cfg_attr(test, type_length_limit = "2434476")]
 #![deny(warnings)]
-#![feature(async_await)]
 
 /// Mononoke pushrebase implementation. The main goal of pushrebase is to decrease push contention.
 /// Commits that client pushed are rebased on top of `onto_bookmark` on the server