logging: Don't forget to save "logging filter all 1"

Prior to this fix, a persistent file or syslog log configuration
didn't work across an application re-start, as the
"logging filter all 1" was never saved and thus no messages were
logged.
diff --git a/src/vty/logging_vty.c b/src/vty/logging_vty.c
index 6166f1f..971ec3b 100644
--- a/src/vty/logging_vty.c
+++ b/src/vty/logging_vty.c
@@ -535,6 +535,10 @@
 		break;
 	}
 
+	vty_out(vty, "  logging filter all %u%s",
+		tgt->filter_map & LOG_FILTER_ALL ? 1 : 0, VTY_NEWLINE);
+	/* FIXME: how to do this for filters outside of libosmocore? */
+
 	vty_out(vty, "  logging color %u%s", tgt->use_color ? 1 : 0,
 		VTY_NEWLINE);
 	vty_out(vty, "  logging timestamp %u%s", tgt->print_timestamp ? 1 : 0,