bug in mount --make-* mountpoint

[Roman Borisov]

Hi,

the analysis of ltp 2010 fs_bind failures showed 3 bugs.
the first test case to show mount --make-rshared issue:

mkdir dir1
busybox mount --bind dir1 dir1
busybox mount --make-rshared dir1

mount returns "mount: can't find dir1 in /etc/fstab" and dies;

in the mount_main() function:

// End of fstab/mtab is reached.
// Were we looking for something specific?
if (argv[0]) { // yes
	long l;
	// If we didn't find anything, complain
	if (!mtcur->mnt_fsname)
		bb_error_msg_and_die("can't find %s in %s",
			argv[0], fstabname);
...

Any of the options like
mount --make-shared mountpoint
mount --make-slave mountpoint
mount --make-private mountpoint
mount --make-unbindable mountpoint
mount --make-rshared mountpoint
mount --make-rslave mountpoint
mount --make-rprivate mountpoint
mount --make-runbindable mountpoint
don't work.

I have no idea about the root of issue yet.

Thanks,
Roman