Unset lto for fuzz, as it conflicts with codegen-units = 1 anyways

Previously, we set `codegen-units = 1` *and* `lto = true` in
`Cargo.toml`, but the docs for `lto` say:

```
No LTO is performed if codegen units is 1 or opt-level is 0.
```
https://doc.rust-lang.org/cargo/reference/profiles.html#lto

Hence, we here remove `lto = true` since it's not used anyways and
confusing.

Author: tnull

fuzz/Cargo.toml

@@ -37,7 +37,6 @@ cc = "1.0"
 members = ["."]
 
 [profile.release]
-lto = true
 codegen-units = 1
 debug-assertions = true
 overflow-checks = true

fuzz/ci-fuzz.sh

@@ -23,7 +23,6 @@ popd
 cargo install --color always --force honggfuzz --no-default-features
 # Because we're fuzzing relatively few iterations, the maximum possible
 # compiler optimizations aren't necessary, so switch to defaults.
-sed -i 's/lto = true//' Cargo.toml
 sed -i 's/codegen-units = 1//' Cargo.toml
 
 export HFUZZ_BUILD_ARGS="--features honggfuzz_fuzz"