This patch adds support for default mount options to be stored in the
superblock, so they don't have to be specified on the mount command line
(or in /etc/fstab).  While I was in the code, I also cleaned up the
handling of how mount options are processed in the ext2 and ext3
filesystems.

Most mount options are now processed *after* the superblock has been
read in.  This allows for a much cleaner handling of those default mount
option parameters that were already stored in the superblock: the
resuid, resgid, and s_errors fields were handled using some fairly gross
special cases.  Now the only mount option which is processed first is
the sb option, which specifies the location of the superblock.  This
allows the handling of all of the default mount parameters to be much
more cleanly and more generally handled.

This does change the behaviour from earlier kernels, in that if the sb
mount option is specified, it must be specified *first*.  However, this
option is rarely used, and if it is, it generally is specified first, so
this seems to be a reasonable restriction.