[PATCH] fix enum pid_directory_inos in proc/base.c

This patch fixes wrongly placed elements in the pid_directory_inos
enum.  Also add comment so this mistake is not repeated.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: <viro@parcelfarce.linux.theplanet.co.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>