If opening any of the log files fail, MaxScale doesn't start before the cause has been removed. Added informative error message which is to be printed to standard error output.

log_manager/log_manager.cc

@@ -2431,9 +2431,16 @@ static bool filewriter_init(
                                                            NULL);
                 }
             
-                if (fw->fwr_file[id] == NULL) {
+                if (fw->fwr_file[id] == NULL) 
+		{
+			fprintf(stderr, 
+				"Error : opening %s failed, %s. Exiting "
+				"MaxScale\n",
+				lf->lf_full_file_name,
+				strerror(errno));
                         goto return_succp;
                 }
+                
                 if (lf->lf_enabled) {
                         start_msg_str = strdup("---\tLogging is enabled.\n");
                 } else {