lib: fix compiler warnings with CURL_DISABLE_NETRC

warning C4189: 'netrc_user_changed': local variable is initialized but
not referenced

warning C4189: 'netrc_passwd_changed': local variable is initialized but
not referenced

Closes #7423

lib/http.c

@@ -850,7 +850,9 @@ Curl_http_output_auth(struct Curl_easy *data,
   /* To prevent the user+password to get sent to other than the original
      host due to a location-follow, we do some weirdo checks here */
   if(!data->state.this_is_a_follow ||
+#ifndef CURL_DISABLE_NETRC
      conn->bits.netrc ||
+#endif
      !data->state.first_host ||
      data->set.allow_auth_to_other_hosts ||
      strcasecompare(data->state.first_host, conn->host.name)) {

lib/url.c

@@ -2887,11 +2887,13 @@ static CURLcode override_login(struct Curl_easy *data,
   char **passwdp = &conn->passwd;
   char **optionsp = &conn->options;
 
+#ifndef CURL_DISABLE_NETRC
   if(data->set.use_netrc == CURL_NETRC_REQUIRED && conn->bits.user_passwd) {
     Curl_safefree(*userp);
     Curl_safefree(*passwdp);
     conn->bits.user_passwd = FALSE; /* disable user+password */
   }
+#endif
 
   if(data->set.str[STRING_OPTIONS]) {
     free(*optionsp);
@@ -2900,6 +2902,7 @@ static CURLcode override_login(struct Curl_easy *data,
       return CURLE_OUT_OF_MEMORY;
   }
 
+#ifndef CURL_DISABLE_NETRC
   conn->bits.netrc = FALSE;
   if(data->set.use_netrc && !data->set.str[STRING_USERNAME]) {
     bool netrc_user_changed = FALSE;
@@ -2925,6 +2928,7 @@ static CURLcode override_login(struct Curl_easy *data,
       conn->bits.user_passwd = TRUE; /* enable user+password */
     }
   }
+#endif
 
   /* for updated strings, we update them in the URL */
   if(*userp) {

lib/urldata.h

@@ -508,7 +508,9 @@ struct ConnectBits {
   BIT(ftp_use_data_ssl); /* Enabled SSL for the data connection */
   BIT(ftp_use_control_ssl); /* Enabled SSL for the control connection */
 #endif
+#ifndef CURL_DISABLE_NETRC
   BIT(netrc);         /* name+password provided by netrc */
+#endif
   BIT(bound); /* set true if bind() has already been done on this socket/
                  connection */
   BIT(multiplex); /* connection is multiplexed */
@@ -1727,8 +1729,10 @@ struct UserDefined {
                                */
   curl_sshkeycallback ssh_keyfunc; /* key matching callback */
   void *ssh_keyfunc_userp;         /* custom pointer to callback */
+#ifndef CURL_DISABLE_NETRC
   enum CURL_NETRC_OPTION
        use_netrc;        /* defined in include/curl.h */
+#endif
   curl_usessl use_ssl;   /* if AUTH TLS is to be attempted etc, for FTP or
                             IMAP or POP3 or others! */
   long new_file_perms;    /* Permissions to use when creating remote files */