orangefs: revamp block sizes

Now the superblock block size is PAGE_SIZE.  The inode block size is
PAGE_SIZE for directories and symlinks, but is the server-reported
block size for regular files.

The block size in the OrangeFS private inode is now deleted.  Stat
now reports PAGE_SIZE for directories and symlinks and the
server-reported block size for regular files.

The user-space visible change is that the block size for directores
and symlinks and the superblock is now PAGE_SIZE rather than the size of
the client-core shared memory buffers, which was typically four
megabytes.

Reported-by: Becky Ligon <ligon@clemson.edu>
Signed-off-by: Martin Brandenburg <martin@omnibond.com>
Cc: hubcap@omnibond.com
Cc: walt@omnibond.com
Signed-off-by: Mike Marshall <hubcap@omnibond.com>