Merge branch 'tcp-mem-pressure-vs-SO_RCVLOWAT'

Eric Dumazet says:

====================
tcp: mem pressure vs SO_RCVLOWAT

First patch fixes an issue for applications using SO_RCVLOWAT
to reduce context switches.

Second patch is a cleanup.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>