[PATCH] procfs: Fix hardlink counts for /proc/<PID>/task

The current logic assumes that a /proc/<PID>/task directory should have a
hardlink count of 3, probably counting ".", "..", and a directory for a
single child task.

It's fairly obvious that this doesn't work out correctly when a PID has
more than one child task, which is quite often the case.

Signed-off-by: Daniel Drake <dsd@gentoo.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>