sheep: support disk more than 2T

Currently we only support disk as backend storage less than 2T due to hardcoded
4M list buffer. The underlying object list cache already return error code when
passed buffer is too small. Simply retry with larger buffer for this case will
allow us enjoy however big disk is and remove this limit.

Signed-off-by: Liu Yuan <tailai.ly@taobao.com>
tests/035: teach it to catch more bugs

Teach test read halt-closed connection. Current master will fail the case.

Signed-off-by: Liu Yuan <tailai.ly@taobao.com>
net: add read timeout for sockfd

This fixes the hang problem demenstated by refined 035 on sheep side.

Signed-off-by: Liu Yuan <tailai.ly@taobao.com>
collie: retry read for eagain

Collie should retry read for eagain to fix the false-timeout case.

This fix the 035 failure on collie side.

Signed-off-by: Liu Yuan <tailai.ly@taobao.com>
checkpatch.pl: reduce an obsolete check

Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>
Signed-off-by: Liu Yuan <tailai.ly@taobao.com>