smp: add all_cpus() helper
smp: add all_cpus() helper

This adds a static method to return a range object to smp.
with this patch it is possible to use:

for (auto i : smp::all_cpus())

Signed-off-by: Amnon Heiman <ed5fc74c4692051ad0b19749fd7cea6ec2d74b9e@cloudius-systems.com>

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