Auto merge of rust-lang#106033 - ChrisDenton:bump-cfg-if, r=Mark-Simulacrum

Remove old version of `cfg-if` by bumping `packed_simd_2` and `getrandom v0.2` versions

```console
> cargo update --package packed_simd_2 --package [email protected]
    Updating crates.io index
    Removing cfg-if v0.1.10
    Updating getrandom v0.2.0 -> v0.2.8
    Updating packed_simd_2 v0.3.4 -> v0.3.8
```

`packed_simd_2` is only used as a dependency of `bytecount` which in turn is only used by `rustfmt`. I can't see any issue with the minor version bump.

The bigger jump is `[email protected]` which is used by a number of things, but 0.2.8 is still semver compatible and there doesn't seem to be any worrying changes (see the [changelog](https://github.com/rust-random/getrandom/blob/master/CHANGELOG.md)). The only breaking change are the removal of XP, stdweb and CloudAbi support but these are not host targets and rustc lacks support for them in any case (stdweb development was [abandonded](https://rustsec.org/advisories/RUSTSEC-2020-0056.html), XP is [tier 3 and `no_std`](https://doc.rust-lang.org/beta/rustc/platform-support.html#tier-3) and CloubAbi is [no longer supported](rust-lang#78439)).

Note that this doesn't affect `[email protected]` which is what std depends on and which is already using the latest version of `cfg-if` (besides, there are already plans to remove that entirely).

Author: bors