smp: Fix smp::submit_to to handle submission to a local cpu
smp: Fix smp::submit_to to handle submission to a local cpu

Handle submission to a local cpu by executing a function immediately
and returning ready future.

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