Update mserv.c

https://mb.srb2.org is now behind CloudFlare, and the Master Server API v1 can not be accessed for some users due to this change. so I setup a new dual stack DNS record for accessing to the API

src/mserv.c

@@ -61,7 +61,7 @@ static CV_PossibleValue_t masterserver_update_rate_cons_t[] = {
 	{0,NULL}
 };
 
-consvar_t cv_masterserver = CVAR_INIT ("masterserver", "https://mb.srb2.org/MS/0", CV_SAVE|CV_CALL, NULL, MasterServer_OnChange);
+consvar_t cv_masterserver = CVAR_INIT ("masterserver", "https://ds.ms.srb2.org/MS/0", CV_SAVE|CV_CALL, NULL, MasterServer_OnChange);
 consvar_t cv_servername = CVAR_INIT ("servername", "SRB2 server", CV_SAVE|CV_NETVAR|CV_CALL|CV_NOINIT|CV_ALLOWLUA, NULL, Update_parameters);
 
 consvar_t cv_masterserver_update_rate = CVAR_INIT ("masterserver_update_rate", "15", CV_SAVE|CV_CALL|CV_NOINIT, masterserver_update_rate_cons_t, Update_parameters);
@@ -544,6 +544,13 @@ static void MasterServer_OnChange(void)
 		CV_StealthSet(&cv_masterserver, cv_masterserver.defaultvalue);
 	}
 
+	if (
+			! cv_masterserver.changed &&
+			strcmp(cv_masterserver.string, "https://mb.srb2.org/MS/0") == 0
+	){
+		CV_StealthSet(&cv_masterserver, cv_masterserver.defaultvalue);
+	}
+
 	Set_api(cv_masterserver.string);
 
 	if (Online())