Remove unused short option from getopt_long() call

The option was removed in 3ce7f72529 but the letter was left in the
getopt_long() call.

src/bin/pg_basebackup/pg_basebackup.c

@@ -2325,7 +2325,7 @@ main(int argc, char **argv)
 
 	atexit(cleanup_directories_atexit);
 
-	while ((c = getopt_long(argc, argv, "CD:F:r:RS:t:T:X:l:nNzZ:d:c:h:p:U:s:wWkvP",
+	while ((c = getopt_long(argc, argv, "CD:F:r:RS:t:T:X:l:nNzZ:d:c:h:p:U:s:wWvP",
 							long_options, &option_index)) != -1)
 	{
 		switch (c)