Functions that use raw pointers should be unsafe

Functions like these are a loophole in Rust's safety:

```rust
pub fn add_cached_mapping(name: *mut i8) -> u64 {
```

```rust
add_cached_mapping(12345 as *mut i8);
```

can cause a segfault despite being "safe".

These functions should be either marked as `unsafe`, or take `CStr`, or a `&'static str` or `&'static [u8]` and checking them for `\0`.