sstables: fix scope problem when writing a vector
sstables: fix scope problem when writing a vector

There is no guarantee that vector tmp will be alive by the time
it's written via output stream. Let's use do_with here.

Signed-off-by: Raphael S. Carvalho <1e2942cea40e3b4d2162dfcd9e53e41c05a84d22@cloudius-systems.com>

senseb/scylla,aruanruan/scylla,scylladb/scylla,duarten/scylla,dwdm/scylla,tempbottle/scylla,shaunstanislaus/scylla,scylladb/scylla,aruanruan/scylla,duarten/scylla,eklitzke/scylla,wildinto/scylla,respu/scylla,tempbottle/scylla,eklitzke/scylla,justintung/scylla,raphaelsc/scylla,respu/scylla,bowlofstew/scylla,avikivity/scylla,senseb/scylla,capturePointer/scylla,glommer/scylla,capturePointer/scylla,linearregression/scylla,gwicke/scylla,acbellini/scylla,guiquanz/scylla,wildinto/scylla,kangkot/scylla,gwicke/scylla,guiquanz/scylla,shaunstanislaus/scylla,dwdm/scylla,kangkot/scylla,kangkot/scylla,justintung/scylla,victorbriz/scylla,glommer/scylla,rluta/scylla,stamhe/scylla,rluta/scylla,phonkee/scylla,asias/scylla,linearregression/scylla,justintung/scylla,kjniemi/scylla,rentongzhang/scylla,rentongzhang/scylla,victorbriz/scylla,shaunstanislaus/scylla,stamhe/scylla,aruanruan/scylla,scylladb/scylla,acbellini/scylla,gwicke/scylla,phonkee/scylla,scylladb/scylla,acbellini/scylla,dwdm/scylla,phonkee/scylla,asias/scylla,victorbriz/scylla,kjniemi/scylla,bowlofstew/scylla,wildinto/scylla,glommer/scylla,duarten/scylla,raphaelsc/scylla,eklitzke/scylla,kjniemi/scylla,rluta/scylla,guiquanz/scylla,stamhe/scylla,capturePointer/scylla,senseb/scylla,tempbottle/scylla,bowlofstew/scylla,respu/scylla,rentongzhang/scylla,avikivity/scylla,avikivity/scylla,linearregression/scylla,raphaelsc/scylla,asias/scylla