[api/compat] PR #465 redefined the language classifier response struct in the API and was casting between incompatible pointer types. Using the exported struct throughout.

src/language_classifier_test.c

@@ -34,7 +34,7 @@ double test_accuracy(char *filename) {
             continue;
         }
 
-        language_classifier_response_t *response = classify_languages(address);
+        libpostal_language_classifier_response_t *response = classify_languages(address);
         if (response == NULL || response->num_languages == 0) {
             printf("%s\tNULL\t%s\n", language, address);
             continue;