CURLOPT_CAPATH: return failure if set without backend support

lib/url.c

@@ -1991,6 +1991,7 @@ CURLcode Curl_setopt(struct SessionHandle *data, CURLoption option,
                        va_arg(param, char *));
     break;
   case CURLOPT_CAPATH:
+#ifdef have_ca_path /* not supported by all backends */
     /*
      * Set CA path info for SSL connection. Specify directory name of the CA
      * certificates which have been prepared using openssl c_rehash utility.
@@ -1998,6 +1999,9 @@ CURLcode Curl_setopt(struct SessionHandle *data, CURLoption option,
     /* This does not work on windows. */
     result = setstropt(&data->set.str[STRING_SSL_CAPATH],
                        va_arg(param, char *));
+#else
+    result = CURLE_NOT_BUILT_IN;
+#endif
     break;
   case CURLOPT_CRLFILE:
     /*