error[E0512]: cannot transmute between types of different sizes, or dependently-sized types

```
error[E0512]: cannot transmute between types of different sizes, or dependently-sized types
--> /usr/ports/devel/crates-io-cli/work/crates-io-cli-4.0.0/cargo-crates/socket2-0.3.15/src/sockaddr.rs:176:9
|
176 | mem::transmute::(v4);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: source type: `SocketAddrV4` (48 bits)
= note: target type: `sockaddr_in` (128 bits)
```

rust-1.66.0
FreeBSD 13.1

Start with crates-io-cli-4.0.0/crates/socket2-0.3.15/src/sockaddr.rs at line 176 and reproduce the E0512 error using Rust 1.66.0 on FreeBSD 13.1. Trace the SocketAddrV4-to-sockaddr_in conversion and identify a compatible resolution; done means the CLI builds without this compiler error.

Written by the indexing model from the issue text.