Added sysfs to list of filesystems not to unmount with umount -a [#190385]

Index: mount/umount.c
===================================================================
--- mount/umount.c.orig
+++ mount/umount.c
@@ -721,7 +721,7 @@ main (int argc, char *argv[]) {
 	if (all) {
 		/* nodev stuff: sysfs, usbfs, oprofilefs, ... */
 		if (types == NULL)
-			types = "noproc,nodevfs,nodevpts";
+			types = "noproc,nodevfs,nodevpts,nosysfs";
 		result = umount_all (types, test_opts);
 	} else if (argc < 1) {
 		usage (stderr, 2);