Libelektra: Rust bindings only works with path dependency

Using dependency from crates.io doesn't work.
I can only use the rust bindings if I compile them in the Elektra proejct first, and then use the compiled (replace macros) directory as a path dependency.

Steps to Reproduce the Problem

# Create a new cargo project
cargo new test-elektra-rs
cd test-elektra-rs
# Add the elektra dependency
echo "elektra = \"0.9\"" >> Cargo.toml
# Build the project
cargo build

Expected Result

Build successful

Actual Result

Error:

error[E0425]: cannot find function `keyIsDirectBelow` in crate `elektra_sys`
   -->CARGO_DIR/registry/src/github.com/elektra-0.9.0/src/readable.rs:231:31
    |
231 |         unsafe { elektra_sys::keyIsDirectBelow(other.as_ref(), self.as_ref()) == 1 }
    |                               ^^^^^^^^^^^^^^^^ help: a function with a similar name exists: `keyIsDirectlyBelow`

error[E0425]: cannot find value `KDB_O_NOCASE` in crate `elektra_sys`
  --> CARGO_DIR/registry/src/github.com/elektra-0.9.0/src/keyset.rs:24:43
   |
24 |         const KDB_O_NOCASE = elektra_sys::KDB_O_NOCASE as elektra_sys::option_t;
   |                                           ^^^^^^^^^^^^ help: a constant with a similar name exists: `KDB_O_NONE`

error[E0425]: cannot find value `KDB_O_WITHOWNER` in crate `elektra_sys`
  --> CARGO_DIR/registry/src/github.com/elektra-0.9.0/src/keyset.rs:26:46
   |
26 |         const KDB_O_WITHOWNER = elektra_sys::KDB_O_WITHOWNER as elektra_sys::option_t;
   |                                              ^^^^^^^^^^^^^^^ not found in `elektra_sys`

error[E0425]: cannot find value `KDB_O_NOALL` in crate `elektra_sys`
  --> CARGO_DIR/registry/src/github.com/elektra-0.9.0/src/keyset.rs:28:42
   |
28 |         const KDB_O_NOALL = elektra_sys::KDB_O_NOALL as elektra_sys::option_t;
   |                                          ^^^^^^^^^^^ help: a constant with a similar name exists: `KDB_O_NONE`

error: aborting due to 4 previous errors

For more information about this error, try `rustc --explain E0425`.
error: could not compile `elektra`.

To learn more, run the command again with --verbose.