Revert "revert "mm: vmscan: do not swap anon pages just because free+file is low""

Revert "revert "mm: vmscan: do not swap anon pages just because free+file is low""

This reverts commit 623762517e2370be3b3f95f4fe08d6c063a49b06.

Ben rightly points out that commit 0bf1457f0cfc, which is what this
original commit was reverting, never ended up in 3.14-stable, but was
only for 3.15.

So revert this patch as we now have the same check twice in a row, which
is pretty pointless.  Although the comments were "prettier"...

Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>