db_clock: Add now_in_usecs() helper function
db_clock: Add now_in_usecs() helper function

Add a helper function similar to FBUtilities.timestampMicros() in origin.

Signed-off-by: Pekka Enberg <add4fcd06328a394f0ad91feda7ee057316dc5ed@cloudius-systems.com>

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