Rollup of 5 pull requests

[jhpratt]

Successful merges:

• Fix unsound dealloc of reborrows from custom allocators #162732 (Fix unsound dealloc of reborrows from custom allocators)
• std::net: clamp multicast ttl value to u8 max. #154113 (std::net: clamp multicast ttl value to u8 max.)
• lint ineffective #[unstable] annotations on re-exports #161178 (lint ineffective #[unstable] annotations on re-exports)
• std: make a lot of items crate private #161612 (std: make a lot of items crate private)
• prevent ICE from derive on repr(packed) enum #162717 (prevent ICE from derive on repr(packed) enum)

r? @ghost

Create a similar rollup

[jhpratt]

@bors r+ p=5

[rust-bors]

📌 Commit b776bdf has been approved by jhpratt

It is now in the queue for this repository.

[rust-log-analyzer]

The job test-arm-android failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[RUSTC-TIMING] rustc_literal_escaper test:false 0.255
warning: unreachable `pub` item
   --> library/std/src/process/tests.rs:368:1
    |
368 | pub fn env_cmd() -> Command {
    | ---^^^^^^^^^^^^^^^^^^^^^^^^
    | |
    | help: consider restricting its visibility: `pub(super)`
    |
    = help: or consider exporting it for use by other crates
note: the lint level is defined here

[rust-bors]

💔 Test for 738f56f failed: CI. Failed job:

• auto - test-arm-android (web logs, enhanced plaintext logs)

[rust-bors]

PR #161612, which is a member of this rollup, was unapproved.