lib: fix unused parameter/function compiler warnings

lib: fix unused parameter/function compiler warnings

- hostip: fix unused variable with `CURL_DISABLE_SHUFFLE_DNS`
  ```
  lib/hostip.c: In function 'Curl_dnscache_mk_entry':
  lib/hostip.c:490:42: warning: unused parameter 'data' [-Wunused-parameter]
    490 | Curl_dnscache_mk_entry(struct Curl_easy *data,
        |                        ~~~~~~~~~~~~~~~~~~^~~~
  ```

- setopt: fix unused function with `CURL_DISABLE_HTTP`
  ```
  lib/setopt.c:214:17: warning: 'httpauth' defined but not used [-Wunused-function]
    214 | static CURLcode httpauth(struct Curl_easy *data, bool proxy,
        |                 ^~~~~~~~
  ```

- url: fix unused function with `CURL_DISABLE_NETRC`
  ```
  lib/url.c:2760:13: warning: 'str_has_ctrl' defined but not used [-Wunused-function]
   2760 | static bool str_has_ctrl(const char *input)
        |             ^~~~~~~~~~~~
  ```

Seen with a minimal curl-for-win build:
```
CW_CONFIG=dev-x64-zero-osnotls-osnoidn-nohttp-nocurltool-linux-unity
```

Closes #17818