sstring: fix string_view interface
sstring: fix string_view interface

string_view is also a template, taking char_type as a parameter.  Need to
use it in order to have a string_view that is compatible with our sstring.

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