quicklist: Set tlb->need_flush if pages are remaining in quicklist 0

This ensures that the quicklists are drained. Otherwise draining may only
occur when the processor reaches an idle state.

Fixes fatal leakage of pgd_t's on 2.6.22 and later.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Reported-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>