Function sign_message 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn sign_message(
    message: *const c_char,
    seckey: *const c_char,
) -> *mut c_char

Signs a message using schnorr signature scheme

Safety

• This function is unsafe because it dereferences and a returns raw pointer.
• ENSURE that result is passed into cstring_free(ptr: *mut c_char) after use.