sys/ps: s/float/int for runtime
sys/ps: s/float/int for runtime

The high precision isn't needed, use per mille instead.
Circumvents printf problems on some platforms.

Also: prevent division by zero.

RIOT-OS/RIOT,rfswarm/RIOT,aeneby/RIOT,openkosmosorg/RIOT,biboc/RIOT,bartfaizoltan/RIOT,LudwigOrtmann/RIOT,kYc0o/RIOT,FrancescoErmini/RIOT,altairpearl/RIOT,wentaoshang/RIOT,bartfaizoltan/RIOT,avmelnikoff/RIOT,robixnai/RIOT,RIOT-OS/RIOT,jremmert-phytec-iot/RIOT,watr-li/RIOT,rakendrathapa/RIOT,kbumsik/RIOT,mziegert/RIOT,RBartz/RIOT,khhhh/RIOT,khhhh/RIOT,robixnai/RIOT,alignan/RIOT,alignan/RIOT,bartfaizoltan/RIOT,zhuoshuguo/RIOT,rakendrathapa/RIOT,EmuxEvans/RIOT,mfrey/RIOT,centurysys/RIOT,roberthartung/RIOT,malosek/RIOT,ThanhVic/RIOT,Osblouf/RIOT,1blankz7/RIOT,daniel-k/RIOT,kb2ma/RIOT,RBartz/RIOT,jfischer-phytec-iot/RIOT,Darredevil/RIOT,l3nko/RIOT,dailab/RIOT,jferreir/RIOT,changbiao/RIOT,AnonMall/RIOT,Ell-i/RIOT,LudwigOrtmann/RIOT,nsol-nmsu/RIOT,rajma996/RIOT,AnonMall/RIOT,chris-wood/RIOT,ntrtrung/RIOT,yogo1212/RIOT,avmelnikoff/RIOT,msolters/RIOT,lebrush/RIOT,bartfaizoltan/RIOT,cladmi/RIOT,marcosalm/RIOT,aeneby/RIOT,Yonezawa-T2/RIOT,beurdouche/RIOT,kYc0o/RIOT,rousselk/RIOT,RubikonAlpha/RIOT,gebart/RIOT,mtausig/RIOT,roberthartung/RIOT,tdautc19841202/RIOT,msolters/RIOT,malosek/RIOT,immesys/RiSyn,attdona/RIOT,latsku/RIOT,rajma996/RIOT,RubikonAlpha/RIOT,x3ro/RIOT,dailab/RIOT,kaspar030/RIOT,plushvoxel/RIOT,alex1818/RIOT,cladmi/RIOT,roberthartung/RIOT,Josar/RIOT,herrfz/RIOT,basilfx/RIOT,LudwigOrtmann/RIOT,luciotorre/RIOT,aeneby/RIOT,A-Paul/RIOT,jasonatran/RIOT,changbiao/RIOT,ros2/ros2_embedded_riot,MarkXYang/RIOT,jasonatran/RIOT,ks156/RIOT,kushalsingh007/RIOT,haoyangyu/RIOT,syin2/RIOT,jremmert-phytec-iot/RIOT,altairpearl/RIOT,herrfz/RIOT,herrfz/RIOT,haoyangyu/RIOT,adrianghc/RIOT,asanka-code/RIOT,lazytech-org/RIOT,rajma996/RIOT,syin2/RIOT,biboc/RIOT,stevenj/RIOT,neiljay/RIOT,chris-wood/RIOT,LudwigOrtmann/RIOT,l3nko/RIOT,neumodisch/RIOT,Darredevil/RIOT,mziegert/RIOT,haoyangyu/RIOT,rfswarm/RIOT,gbarnett/RIOT,BytesGalore/PetersRIOT,nsol-nmsu/RIOT,BytesGalore/PetersRIOT,wentaoshang/RIOT,thiagohd/RIOT,nsol-nmsu/RIOT,OlegHahm/RIOT,JensErdmann/RIOT,Hyungsin/RIOT-OS,TobiasFredersdorf/RIOT,mtausig/RIOT,rfswarm2/RIOT,Yonezawa-T2/RIOT,jfischer-phytec-iot/RIOT,jfischer-phytec-iot/RIOT,alex1818/RIOT,shady33/RIOT,zhuoshuguo/RIOT,MohmadAyman/RIOT,rakendrathapa/RIOT,marcosalm/RIOT,Darredevil/RIOT,emmanuelsearch/RIOT,daniel-k/RIOT,gebart/RIOT,rfswarm2/RIOT,ks156/RIOT,beurdouche/RIOT,cladmi/RIOT,EmuxEvans/RIOT,katezilla/RIOT,locicontrols/RIOT,authmillenon/RIOT,lebrush/RIOT,backenklee/RIOT,Darredevil/RIOT,alex1818/RIOT,openkosmosorg/RIOT,kb2ma/RIOT,1blankz7/RIOT,adjih/RIOT,ximus/RIOT,kaleb-himes/RIOT,adjih/RIOT,mfrey/RIOT,kushalsingh007/RIOT,x3ro/RIOT,OTAkeys/RIOT,d00616/RIOT,khhhh/RIOT,haoyangyu/RIOT,d00616/RIOT,kaspar030/RIOT,locicontrols/RIOT,1blankz7/RIOT,chris-wood/RIOT,A-Paul/RIOT,robixnai/RIOT,ros2/ros2_embedded_riot,Hyungsin/RIOT-OS,1blankz7/RIOT,marcosalm/RIOT,JensErdmann/RIOT,PSHIVANI/Riot-Code,neiljay/RIOT,altairpearl/RIOT,l3nko/RIOT,wentaoshang/RIOT,thomaseichinger/RIOT,yogo1212/RIOT,gbarnett/RIOT,OlegHahm/RIOT,kaleb-himes/RIOT,josephnoir/RIOT,kaspar030/RIOT,l3nko/RIOT,luciotorre/RIOT,lebrush/RIOT,dhruvvyas90/RIOT,stevenj/RIOT,MarkXYang/RIOT,msolters/RIOT,Osblouf/RIOT,jbeyerstedt/RIOT-OTA-update,koenning/RIOT,RubikonAlpha/RIOT,EmuxEvans/RIOT,centurysys/RIOT,BytesGalore/RIOT,herrfz/RIOT,beurdouche/RIOT,msolters/RIOT,kerneltask/RIOT,watr-li/RIOT,rfswarm2/RIOT,patkan/RIOT,fnack/RIOT,toonst/RIOT,rfswarm/RIOT,locicontrols/RIOT,ks156/RIOT,alignan/RIOT,RIOT-OS/RIOT,zhuoshuguo/RIOT,patkan/RIOT,immesys/RiSyn,Lotterleben/RIOT,abp719/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT,kerneltask/RIOT,gautric/RIOT,patkan/RIOT,miri64/RIOT,kushalsingh007/RIOT,stevenj/RIOT,ximus/RIOT,shady33/RIOT,Ell-i/RIOT,stevenj/RIOT,FrancescoErmini/RIOT,alex1818/RIOT,Darredevil/RIOT,abkam07/RIOT,daniel-k/RIOT,RBartz/RIOT,hamilton-mote/RIOT-OS,OlegHahm/RIOT,biboc/RIOT,ant9000/RIOT,aeneby/RIOT,Lotterleben/RIOT,DipSwitch/RIOT,automote/RIOT,attdona/RIOT,dhruvvyas90/RIOT,sgso/RIOT,FrancescoErmini/RIOT,dailab/RIOT,EmuxEvans/RIOT,phiros/RIOT,watr-li/RIOT,asanka-code/RIOT,arvindpdmn/RIOT,plushvoxel/RIOT,gebart/RIOT,herrfz/RIOT-old,sumanpanchal/RIOT,BytesGalore/RIOT,asanka-code/RIOT,jhollister/RIOT,LudwigKnuepfer/RIOT,sgso/RIOT,dkm/RIOT,lazytech-org/RIOT,fnack/RIOT,dailab/RIOT,adjih/RIOT,l3nko/RIOT,ntrtrung/RIOT,BytesGalore/PetersRIOT,1blankz7/RIOT,jferreir/RIOT,tfar/RIOT,centurysys/RIOT,MonsterCode8000/RIOT,ximus/RIOT,emmanuelsearch/RIOT,neiljay/RIOT,jhollister/RIOT,haoyangyu/RIOT,mziegert/RIOT,ros2/ros2_embedded_riot,Lexandro92/RIOT-CoAP,immesys/RiSyn,patkan/RIOT,kaspar030/RIOT,biboc/RIOT,d00616/RIOT,neumodisch/RIOT,daniel-k/RIOT,adrianghc/RIOT,robixnai/RIOT,ThanhVic/RIOT,phiros/RIOT,ros2/ros2_embedded_riot,DipSwitch/RIOT,dkm/RIOT,fnack/RIOT,katezilla/RIOT,malosek/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT,abp719/RIOT,changbiao/RIOT,TobiasFredersdorf/RIOT,Lotterleben/RIOT,MonsterCode8000/RIOT,rfuentess/RIOT,kb2ma/RIOT,ntrtrung/RIOT,zhuoshuguo/RIOT,kYc0o/RIOT,Josar/RIOT,MonsterCode8000/RIOT,attdona/RIOT,smlng/RIOT,BytesGalore/PetersRIOT,sumanpanchal/RIOT,luciotorre/RIOT,benoit-canet/RIOT,thomaseichinger/RIOT,hamilton-mote/RIOT-OS,josephnoir/RIOT,avmelnikoff/RIOT,FrancescoErmini/RIOT,RubikonAlpha/RIOT,kushalsingh007/RIOT,basilfx/RIOT,roberthartung/RIOT,ks156/RIOT,ThanhVic/RIOT,abp719/RIOT,dhruvvyas90/RIOT,katezilla/RIOT,plushvoxel/RIOT,automote/RIOT,zhuoshuguo/RIOT,syin2/RIOT,rfswarm2/RIOT,mtausig/RIOT,tdautc19841202/RIOT,binarylemon/RIOT,arvindpdmn/RIOT,brettswann/RIOT,patkan/RIOT,syin2/RIOT,rousselk/RIOT,JensErdmann/RIOT,khhhh/RIOT,miri64/RIOT,backenklee/RIOT,plushvoxel/RIOT,alignan/RIOT,mziegert/RIOT,jferreir/RIOT,beurdouche/RIOT,jferreir/RIOT,rfswarm/RIOT,BytesGalore/RIOT,kbumsik/RIOT,bartfaizoltan/RIOT,dkm/RIOT,brettswann/RIOT,chris-wood/RIOT,ant9000/RIOT,changbiao/RIOT,kYc0o/RIOT,abkam07/RIOT,ros2/ros2_embedded_riot,thomaseichinger/RIOT,abp719/RIOT,khhhh/RIOT,abkam07/RIOT,altairpearl/RIOT,Ell-i/RIOT,jhollister/RIOT,abp719/RIOT,jasonatran/RIOT,herrfz/RIOT-old,mfrey/RIOT,PSHIVANI/Riot-Code,backenklee/RIOT,changbiao/RIOT,luciotorre/RIOT,LudwigOrtmann/RIOT,immesys/RiSyn,dkm/RIOT,kbumsik/RIOT,fnack/RIOT,tdautc19841202/RIOT,rakendrathapa/RIOT,fnack/RIOT,plushvoxel/RIOT,BytesGalore/PetersRIOT,Lotterleben/RIOT,DipSwitch/RIOT,haoyangyu/RIOT,automote/RIOT,authmillenon/RIOT,PSHIVANI/Riot-Code,LudwigKnuepfer/RIOT,d00616/RIOT,neiljay/RIOT,Yonezawa-T2/RIOT,jhollister/RIOT,jfischer-phytec-iot/RIOT,changbiao/RIOT,locicontrols/RIOT,sgso/RIOT,gautric/RIOT,Lexandro92/RIOT-CoAP,MohmadAyman/RIOT,thomaseichinger/RIOT,Josar/RIOT,daniel-k/RIOT,MonsterCode8000/RIOT,rousselk/RIOT,centurysys/RIOT,stevenj/RIOT,dkm/RIOT,koenning/RIOT,ThanhVic/RIOT,miri64/RIOT,chris-wood/RIOT,LudwigKnuepfer/RIOT,arvindpdmn/RIOT,l3nko/RIOT,kerneltask/RIOT,RBartz/RIOT,aeneby/RIOT,jfischer-phytec-iot/RIOT,dailab/RIOT,LudwigOrtmann/RIOT,brettswann/RIOT,jremmert-phytec-iot/RIOT,toonst/RIOT,sumanpanchal/RIOT,MarkXYang/RIOT,ximus/RIOT,authmillenon/RIOT,RBartz/RIOT,JensErdmann/RIOT,yogo1212/RIOT,JensErdmann/RIOT,Hyungsin/RIOT-OS,alex1818/RIOT,kerneltask/RIOT,thomaseichinger/RIOT,altairpearl/RIOT,jasonatran/RIOT,luciotorre/RIOT,locicontrols/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT,basilfx/RIOT,gautric/RIOT,thiagohd/RIOT,EmuxEvans/RIOT,ximus/RIOT,koenning/RIOT,tdautc19841202/RIOT,asanka-code/RIOT,gbarnett/RIOT,rakendrathapa/RIOT,herrfz/RIOT-old,wentaoshang/RIOT,ros2/ros2_embedded_riot,adjih/RIOT,OlegHahm/RIOT,smlng/RIOT,tfar/RIOT,rfuentess/RIOT,arvindpdmn/RIOT,DipSwitch/RIOT,latsku/RIOT,Yonezawa-T2/RIOT,PSHIVANI/Riot-Code,dhruvvyas90/RIOT,koenning/RIOT,shady33/RIOT,MonsterCode8000/RIOT,sumanpanchal/RIOT,x3ro/RIOT,thiagohd/RIOT,hamilton-mote/RIOT-OS,immesys/RiSyn,EmuxEvans/RIOT,thiagohd/RIOT,robixnai/RIOT,latsku/RIOT,khhhh/RIOT,herrfz/RIOT,rousselk/RIOT,Lexandro92/RIOT-CoAP,Hyungsin/RIOT-OS,adrianghc/RIOT,jferreir/RIOT,ant9000/RIOT,attdona/RIOT,alignan/RIOT,Osblouf/RIOT,malosek/RIOT,automote/RIOT,kbumsik/RIOT,gbarnett/RIOT,katezilla/RIOT,1blankz7/RIOT,centurysys/RIOT,OTAkeys/RIOT,brettswann/RIOT,avmelnikoff/RIOT,mtausig/RIOT,tfar/RIOT,binarylemon/RIOT,basilfx/RIOT,miri64/RIOT,MohmadAyman/RIOT,jbeyerstedt/RIOT-OTA-update,kYc0o/RIOT,phiros/RIOT,jremmert-phytec-iot/RIOT,Ell-i/RIOT,emmanuelsearch/RIOT,mziegert/RIOT,neumodisch/RIOT,robixnai/RIOT,katezilla/RIOT,rajma996/RIOT,jbeyerstedt/RIOT-OTA-update,d00616/RIOT,roberthartung/RIOT,RIOT-OS/RIOT,automote/RIOT,asanka-code/RIOT,toonst/RIOT,syin2/RIOT,Hyungsin/RIOT-OS,latsku/RIOT,phiros/RIOT,OTAkeys/RIOT,Josar/RIOT,yogo1212/RIOT,sumanpanchal/RIOT,TobiasFredersdorf/RIOT,OTAkeys/RIOT,herrfz/RIOT-old,lazytech-org/RIOT,Josar/RIOT,nsol-nmsu/RIOT,sumanpanchal/RIOT,malosek/RIOT,kbumsik/RIOT,mtausig/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT,neiljay/RIOT,jremmert-phytec-iot/RIOT,RubikonAlpha/RIOT,rousselk/RIOT,BytesGalore/PetersRIOT,BytesGalore/RIOT,FrancescoErmini/RIOT,Ell-i/RIOT,Lotterleben/RIOT,thiagohd/RIOT,rfuentess/RIOT,wentaoshang/RIOT,koenning/RIOT,rakendrathapa/RIOT,lebrush/RIOT,MonsterCode8000/RIOT,sgso/RIOT,arvindpdmn/RIOT,openkosmosorg/RIOT,centurysys/RIOT,altairpearl/RIOT,rfswarm2/RIOT,neumodisch/RIOT,emmanuelsearch/RIOT,ros2/ros2_embedded_riot,lazytech-org/RIOT,LudwigKnuepfer/RIOT,lebrush/RIOT,abkam07/RIOT,FrancescoErmini/RIOT,benoit-canet/RIOT,binarylemon/RIOT,Osblouf/RIOT,ximus/RIOT,kaleb-himes/RIOT,ThanhVic/RIOT,adjih/RIOT,josephnoir/RIOT,benoit-canet/RIOT,watr-li/RIOT,latsku/RIOT,authmillenon/RIOT,immesys/RiSyn,AnonMall/RIOT,rfuentess/RIOT,kushalsingh007/RIOT,lebrush/RIOT,RBartz/RIOT,binarylemon/RIOT,Lotterleben/RIOT,abkam07/RIOT,mfrey/RIOT,backenklee/RIOT,locicontrols/RIOT,beurdouche/RIOT,d00616/RIOT,rfswarm/RIOT,abp719/RIOT,msolters/RIOT,marcosalm/RIOT,jasonatran/RIOT,josephnoir/RIOT,attdona/RIOT,watr-li/RIOT,gbarnett/RIOT,nsol-nmsu/RIOT,Lexandro92/RIOT-CoAP,arvindpdmn/RIOT,wentaoshang/RIOT,stevenj/RIOT,neumodisch/RIOT,jhollister/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT,gautric/RIOT,msolters/RIOT,ThanhVic/RIOT,PSHIVANI/Riot-Code,jremmert-phytec-iot/RIOT,gbarnett/RIOT,ntrtrung/RIOT,gebart/RIOT,TobiasFredersdorf/RIOT,jbeyerstedt/RIOT-OTA-update,authmillenon/RIOT,OlegHahm/RIOT,kaleb-himes/RIOT,lazytech-org/RIOT,shady33/RIOT,MohmadAyman/RIOT,hamilton-mote/RIOT-OS,sgso/RIOT,ntrtrung/RIOT,TobiasFredersdorf/RIOT,kb2ma/RIOT,herrfz/RIOT-old,dhruvvyas90/RIOT,patkan/RIOT,A-Paul/RIOT,jbeyerstedt/RIOT-OTA-update,kb2ma/RIOT,tdautc19841202/RIOT,kushalsingh007/RIOT,smlng/RIOT,avmelnikoff/RIOT,latsku/RIOT,Yonezawa-T2/RIOT,daniel-k/RIOT,cladmi/RIOT,cladmi/RIOT,Osblouf/RIOT,adrianghc/RIOT,brettswann/RIOT,bartfaizoltan/RIOT,attdona/RIOT,hamilton-mote/RIOT-OS,asanka-code/RIOT,thiagohd/RIOT,MarkXYang/RIOT,tfar/RIOT,ant9000/RIOT,basilfx/RIOT,malosek/RIOT,fnack/RIOT,rajma996/RIOT,automote/RIOT,abkam07/RIOT,PSHIVANI/Riot-Code,miri64/RIOT,ntrtrung/RIOT,brettswann/RIOT,phiros/RIOT,authmillenon/RIOT,alex1818/RIOT,rfswarm/RIOT,josephnoir/RIOT,rousselk/RIOT,benoit-canet/RIOT,rajma996/RIOT,jferreir/RIOT,DipSwitch/RIOT,openkosmosorg/RIOT,kerneltask/RIOT,ant9000/RIOT,A-Paul/RIOT,AnonMall/RIOT,marcosalm/RIOT,backenklee/RIOT,neumodisch/RIOT,adrianghc/RIOT,biboc/RIOT,JensErdmann/RIOT,smlng/RIOT,yogo1212/RIOT,MohmadAyman/RIOT,locicontrols/RIOT,shady33/RIOT,x3ro/RIOT,A-Paul/RIOT,jhollister/RIOT,OTAkeys/RIOT,Lexandro92/RIOT-CoAP,sgso/RIOT,Darredevil/RIOT,smlng/RIOT,AnonMall/RIOT,zhuoshuguo/RIOT,benoit-canet/RIOT,binarylemon/RIOT,MarkXYang/RIOT,mziegert/RIOT,yogo1212/RIOT,Osblouf/RIOT,kaspar030/RIOT,Lexandro92/RIOT-CoAP,mfrey/RIOT,Lotterleben/RIOT,AnonMall/RIOT,BytesGalore/PetersRIOT,kaleb-himes/RIOT,openkosmosorg/RIOT,emmanuelsearch/RIOT,tdautc19841202/RIOT,emmanuelsearch/RIOT,luciotorre/RIOT,tfar/RIOT,LudwigKnuepfer/RIOT,toonst/RIOT,toonst/RIOT,BytesGalore/RIOT,dhruvvyas90/RIOT,gebart/RIOT,koenning/RIOT,MarkXYang/RIOT,shady33/RIOT,marcosalm/RIOT,openkosmosorg/RIOT,ks156/RIOT,Yonezawa-T2/RIOT,RubikonAlpha/RIOT,gautric/RIOT,watr-li/RIOT,DipSwitch/RIOT,MohmadAyman/RIOT,rfswarm2/RIOT,rfuentess/RIOT,phiros/RIOT,RIOT-OS/RIOT,benoit-canet/RIOT,herrfz/RIOT,binarylemon/RIOT,x3ro/RIOT,chris-wood/RIOT