Upgrade to cohttp-0.11.2

Signed-off-by: Jon Ludlam <jonathan.ludlam@eu.citrix.com>
rrd_client: bypass the message switch

xcp-rrdd is not yet message-switch aware. Therefore all users
should continue to use the Unix domain sockets for now.

Signed-off-by: David Scott <dave.scott@citrix.com>
Merge pull request #13 from djs55/rrd-should-bypass-switch

rrd_client: bypass the message switch
Merge pull request #24 from jonludlam/cohttp-0.11.2

Upgrade to cohttp-0.11.2