sstring: introduce release()
sstring: introduce release()

Releases owenrship of the data and gives it away as
temporary_buffer. This way we can avoid allocation when putting rvalue
sstring if it's already using external storage. Except we need to
allocate a deleter which uses delete[], but this can be fixed later.

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