## Proposed Changes
Allowing compiling without MDBX by running:
```bash
CARGO_INSTALL_EXTRA_FLAGS="--no-default-features" make
```
The reasons to do this are several:
- Save compilation time if the slasher won't be used
- Work around compilation errors in slasher backend dependencies (our pinned version of MDBX is currently not compiling on FreeBSD with certain compiler versions).
## Additional Info
When I opened this PR we were using resolver v1 which [doesn't disable default features in dependencies](https://doc.rust-lang.org/cargo/reference/features.html#resolver-version-2-command-line-flags), and `mdbx` is default for the `slasher` crate. Even after the resolver got changed to v2 in #3697 compiling with `--no-default-features` _still_ wasn't turning off the slasher crate's default features, so I added `default-features = false` in all the places we depend on it.
Co-authored-by: Michael Sproul <micsproul@gmail.com>
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