shared_ptr: fix uninitialized enable_shared_from_this ref count
shared_ptr: fix uninitialized enable_shared_from_this ref count

Caused immediate leak.

norcimo5/seastar,bowlofstew/seastar,tempbottle/scylla,hongliangzhao/seastar,wildinto/seastar,asias/scylla,bzero/seastar,syuu1228/seastar,glommer/scylla,tempbottle/scylla,flashbuckets/seastar,eklitzke/scylla,linearregression/seastar,aruanruan/scylla,rluta/scylla,kangkot/scylla,victorbriz/scylla,kjniemi/scylla,raphaelsc/scylla,linearregression/seastar,dwdm/scylla,ducthangho/imdb,koolhazz/seastar,stamhe/scylla,bowlofstew/scylla,linearregression/seastar,joerg84/seastar,kangkot/scylla,slivne/seastar,senseb/scylla,asias/scylla,rluta/scylla,slivne/seastar,wildinto/scylla,capturePointer/scylla,guiquanz/scylla,avikivity/seastar,avikivity/seastar,mixja/seastar,dwdm/scylla,xtao/seastar,stamhe/seastar,justintung/scylla,tempbottle/scylla,phonkee/scylla,cloudius-systems/seastar,sjperkins/seastar,chunshengster/seastar,syuu1228/seastar,bowlofstew/scylla,chunshengster/seastar,shyamalschandra/seastar,hongliangzhao/seastar,anzihenry/seastar,gwicke/scylla,glommer/scylla,avikivity/scylla,kjniemi/scylla,norcimo5/seastar,dwdm/seastar,scylladb/seastar,kjniemi/seastar,senseb/scylla,jonathanleang/seastar,eklitzke/scylla,tempbottle/seastar,scylladb/scylla-seastar,sjperkins/seastar,shaunstanislaus/scylla,aruanruan/scylla,duarten/scylla,bzero/seastar,sjperkins/seastar,bowlofstew/seastar,acbellini/scylla,stamhe/seastar,acbellini/scylla,acbellini/scylla,wildinto/seastar,asias/scylla,joerg84/seastar,dwdm/scylla,respu/scylla,justintung/scylla,scylladb/scylla,phonkee/scylla,guiquanz/scylla,dwdm/seastar,anzihenry/seastar,mixja/seastar,linearregression/scylla,avikivity/scylla,duarten/scylla,xtao/seastar,cloudius-systems/seastar,eklitzke/scylla,wildinto/seastar,scylladb/scylla,avikivity/scylla,leejir/seastar,ducthangho/imdb,gwicke/scylla,capturePointer/scylla,jonathanleang/seastar,joerg84/seastar,linearregression/scylla,shaunstanislaus/scylla,scylladb/scylla-seastar,printedheart/seastar,victorbriz/scylla,acbellini/seastar,respu/scylla,printedheart/seastar,dreamsxin/seastar,flashbuckets/seastar,tempbottle/seastar,rluta/scylla,aruanruan/scylla,scylladb/seastar,raphaelsc/seastar,hongliangzhao/seastar,raphaelsc/scylla,kjniemi/scylla,capturePointer/scylla,mixja/seastar,scylladb/scylla-seastar,shaunstanislaus/scylla,ducthangho/imdb,stamhe/scylla,phonkee/scylla,cloudius-systems/seastar,shyamalschandra/seastar,acbellini/seastar,bowlofstew/seastar,bzero/seastar,scylladb/seastar,scylladb/scylla,printedheart/seastar,rentongzhang/scylla,flashbuckets/seastar,wildinto/scylla,acbellini/seastar,tempbottle/seastar,stamhe/seastar,gwicke/scylla,wildinto/scylla,chunshengster/seastar,norcimo5/seastar,leejir/seastar,respu/scylla,syuu1228/seastar,kjniemi/seastar,glommer/scylla,anzihenry/seastar,shyamalschandra/seastar,scylladb/scylla,dreamsxin/seastar,avikivity/seastar,victorbriz/scylla,slivne/seastar,kangkot/scylla,rentongzhang/scylla,senseb/scylla,koolhazz/seastar,bowlofstew/scylla,guiquanz/scylla,raphaelsc/seastar,leejir/seastar,kjniemi/seastar,duarten/scylla,koolhazz/seastar,dreamsxin/seastar,jonathanleang/seastar,raphaelsc/scylla,justintung/scylla,rentongzhang/scylla,linearregression/scylla,raphaelsc/seastar,dwdm/seastar,stamhe/scylla,xtao/seastar