Clean up several things in the xattr code, and prepare it for
in-inode attributes:

* Add the ext3_xattr_check_names, ext3_xattr_check_block, and
  ext3_xattr_check_entry functions for checking xattr data
  structures.
* Add the ext3_xattr_find_entry, ext3_xattr_list_entries, and
  ext3_xattr_set_entry functions for manipulating xattr entries.
  Switch to using these functions in ext3_xattr_get,
  ext3_xattr_list, and ext3_xattr_set_handle.
* Merge ext3_xattr_set_handle and ext3_xattr_set_handle2.
* Rename the HDR and FIRST_ENTRY macros.
* We have no way to deal with a ext3_xattr_cache_insert failure,
  so make it return void.
* Make the debug messages more useful.
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>