reactor: avoid SIGPIPE when writing to a socket
reactor: avoid SIGPIPE when writing to a socket

We don't handle SIGPIPE, so ask the kernel not to send one by using sendmsg()
with MSG_NOSIGNAL.

anzihenry/seastar,cloudius-systems/seastar,sjperkins/seastar,chunshengster/seastar,dwdm/seastar,printedheart/seastar,norcimo5/seastar,jonathanleang/seastar,anzihenry/seastar,bowlofstew/seastar,scylladb/scylla-seastar,linearregression/seastar,norcimo5/seastar,bowlofstew/seastar,sjperkins/seastar,joerg84/seastar,shyamalschandra/seastar,tempbottle/seastar,cloudius-systems/seastar,tempbottle/seastar,scylladb/scylla-seastar,flashbuckets/seastar,koolhazz/seastar,hongliangzhao/seastar,cloudius-systems/seastar,hongliangzhao/seastar,koolhazz/seastar,flashbuckets/seastar,scylladb/seastar,kjniemi/seastar,dreamsxin/seastar,linearregression/seastar,bowlofstew/seastar,dreamsxin/seastar,scylladb/seastar,dwdm/seastar,avikivity/seastar,acbellini/seastar,printedheart/seastar,flashbuckets/seastar,syuu1228/seastar,mixja/seastar,hongliangzhao/seastar,wildinto/seastar,stamhe/seastar,dwdm/seastar,scylladb/scylla-seastar,dreamsxin/seastar,avikivity/seastar,joerg84/seastar,avikivity/seastar,xtao/seastar,leejir/seastar,chunshengster/seastar,acbellini/seastar,shyamalschandra/seastar,leejir/seastar,wildinto/seastar,wildinto/seastar,kjniemi/seastar,mixja/seastar,joerg84/seastar,norcimo5/seastar,chunshengster/seastar,stamhe/seastar,kjniemi/seastar,linearregression/seastar,shyamalschandra/seastar,stamhe/seastar,syuu1228/seastar,syuu1228/seastar,tempbottle/seastar,xtao/seastar,jonathanleang/seastar,anzihenry/seastar,printedheart/seastar,jonathanleang/seastar,xtao/seastar,mixja/seastar,acbellini/seastar,koolhazz/seastar,scylladb/seastar,leejir/seastar,sjperkins/seastar