logging_vty: Fix saving of "logging print file .. last"

Back in 2018 in I393907b3c9e0cc1145e102328adad0a83ee13a9f Neels
introduced "last" as an optional flag to log the file/line number at the
end of the line, rather than at the end of the header.  It seems nobody
has been usingi this feature, or at least never tried to save a related
config file, as there was no code whatsoever that would ever save this
optional "last" flag.

Change-Id: I7b6245256aecc425722242aaabc154ac58ba27a0
diff --git a/src/vty/logging_vty.c b/src/vty/logging_vty.c
index 0282350..6a7a8f4 100644
--- a/src/vty/logging_vty.c
+++ b/src/vty/logging_vty.c
@@ -1010,8 +1010,9 @@
 			tgt->print_timestamp ? 1 : 0, VTY_NEWLINE);
 	if (tgt->print_level)
 		vty_out(vty, " logging print level 1%s", VTY_NEWLINE);
-	vty_out(vty, " logging print file %s%s",
+	vty_out(vty, " logging print file %s%s%s",
 		get_value_string(logging_print_file_args, tgt->print_filename2),
+		tgt->print_filename_pos == LOG_FILENAME_POS_LINE_END ? " last" : "",
 		VTY_NEWLINE);
 
 	if (tgt->loglevel) {