Changed nimprof.hook() to handle uninitialized t0
Changed nimprof.hook() to handle uninitialized t0

It's unlikely, but possible for the conversion to nanoseconds
to overflow if QueryPerformanceCounter() returns a
large enough timestamp.  This change avoids that, at the
cost of always taking a sample the first time through
when t0 == 0.

fmamud/Nim,russpowers/Nim,tulayang/Nim,Dhertz/Nim,haiodo/Nim,Matt14916/Nim,sferik/Nim,BlaXpirit/nim,jsanjuas/Nim,russpowers/Nim,bvssvni/Nim,Dhertz/Nim,sarvex/Nim-lang,greyanubis/Nim,nanoant/Nim,nafsaka/Nim,nanoant/Nim,gokr/Nim,Matt14916/Nim,msmith491/Nim,SSPkrolik/Nim,sferik/Nim,mbaulch/Nim,nanoant/Nim,zachaysan/Nim,xland/Nim,singularperturbation/Nim,greyanubis/Nim,zachaysan/Nim,fredericksilva/Nim,singularperturbation/Nim,fredericksilva/Nim,Salafit/Nim,sferik/Nim,greyanubis/Nim,nimLuckyBull/Nim,MrJohz/Nim,fredericksilva/Nim,gokr/Nim,nimLuckyBull/Nim,xland/Nim,tmm1/Nim,endragor/Nim,Dhertz/Nim,endragor/Nim,Matt14916/Nim,Salafit/Nim,xland/Nim,jfhg/Nim,SSPkrolik/Nim,mbaulch/Nim,tmm1/Nim,reactormonk/nim,haiodo/Nim,Matt14916/Nim,jsanjuas/Nim,dom96/Nim,Salafit/Nim,sarvex/Nim-lang,judofyr/Nim,singularperturbation/Nim,reactormonk/nim,BlaXpirit/nim,fmamud/Nim,douglas-larocca/Nim,MrJohz/Nim,kirbyfan64/Nim,bvssvni/Nim,mbaulch/Nim,gokr/Nim,russpowers/Nim,Dhertz/Nim,judofyr/Nim,greyanubis/Nim,reactormonk/nim,JCavallo/Nim,Dhertz/Nim,dom96/Nim,SSPkrolik/Nim,bvssvni/Nim,kirbyfan64/Nim,haiodo/Nim,douglas-larocca/Nim,Salafit/Nim,BlaXpirit/nim,nimLuckyBull/Nim,endragor/Nim,zachaysan/Nim,tulayang/Nim,jsanjuas/Nim,BlaXpirit/nim,sarvex/Nim-lang,nafsaka/Nim,kirbyfan64/Nim,douglas-larocca/Nim,bvssvni/Nim,fredericksilva/Nim,Salafit/Nim,reactormonk/nim,haiodo/Nim,MrJohz/Nim,jsanjuas/Nim,tmm1/Nim,sferik/Nim,endragor/Nim,JCavallo/Nim,russpowers/Nim,gokr/Nim,JCavallo/Nim,nafsaka/Nim,jsanjuas/Nim,russpowers/Nim,fmamud/Nim,Senketsu/Nim,nanoant/Nim,sarvex/Nim-lang,sarvex/Nim-lang,endragor/Nim,SSPkrolik/Nim,BlaXpirit/nim,Dhertz/Nim,nafsaka/Nim,reactormonk/nim,sferik/Nim,zachaysan/Nim,greyanubis/Nim,Matt14916/Nim,sarvex/Nim-lang,kirbyfan64/Nim,Senketsu/Nim,douglas-larocca/Nim,douglas-larocca/Nim,jfhg/Nim,haiodo/Nim,russpowers/Nim,Matt14916/Nim,judofyr/Nim,fredericksilva/Nim,nafsaka/Nim,singularperturbation/Nim,tmm1/Nim,JCavallo/Nim,gokr/Nim,greyanubis/Nim,dom96/Nim,xland/Nim,nanoant/Nim,bvssvni/Nim,msmith491/Nim,reactormonk/nim,nafsaka/Nim,dom96/Nim,nimLuckyBull/Nim,MrJohz/Nim,douglas-larocca/Nim,fmamud/Nim,zachaysan/Nim,kirbyfan64/Nim,Senketsu/Nim,judofyr/Nim,tmm1/Nim,mbaulch/Nim,jsanjuas/Nim,douglas-larocca/Nim,Salafit/Nim,MrJohz/Nim,reactormonk/nim,nafsaka/Nim,endragor/Nim,tulayang/Nim,judofyr/Nim,SSPkrolik/Nim,sferik/Nim,nimLuckyBull/Nim,douglas-larocca/Nim,mbaulch/Nim,nanoant/Nim,fredericksilva/Nim,dom96/Nim,fmamud/Nim,judofyr/Nim,tmm1/Nim,xland/Nim,mbaulch/Nim,mbaulch/Nim,tulayang/Nim,dom96/Nim,jfhg/Nim,judofyr/Nim,MrJohz/Nim,endragor/Nim,JCavallo/Nim,bvssvni/Nim,singularperturbation/Nim,tulayang/Nim,fredericksilva/Nim,fmamud/Nim,jfhg/Nim,Senketsu/Nim,russpowers/Nim,Salafit/Nim,jfhg/Nim,haiodo/Nim,tulayang/Nim,Senketsu/Nim,zachaysan/Nim,zachaysan/Nim,JCavallo/Nim,kirbyfan64/Nim,singularperturbation/Nim,sferik/Nim,sarvex/Nim-lang,nimLuckyBull/Nim,nanoant/Nim,MrJohz/Nim,SSPkrolik/Nim,kirbyfan64/Nim,msmith491/Nim,jsanjuas/Nim,Dhertz/Nim,tmm1/Nim,Senketsu/Nim,JCavallo/Nim,msmith491/Nim,judofyr/Nim,jfhg/Nim,kirbyfan64/Nim,fmamud/Nim,jfhg/Nim,BlaXpirit/nim,nimLuckyBull/Nim,SSPkrolik/Nim,gokr/Nim,BlaXpirit/nim,Matt14916/Nim,msmith491/Nim,reactormonk/nim,fredericksilva/Nim,singularperturbation/Nim,BlaXpirit/nim,sferik/Nim,Senketsu/Nim,xland/Nim,dom96/Nim,greyanubis/Nim,gokr/Nim,haiodo/Nim,gokr/Nim,SSPkrolik/Nim,bvssvni/Nim,msmith491/Nim,msmith491/Nim,xland/Nim