chronos: Fix stdio warnings
chronos: Fix stdio warnings

altairpearl/RIOT,x3ro/RIOT,josephnoir/RIOT,aeneby/RIOT,cladmi/RIOT,adrianghc/RIOT,kaleb-himes/RIOT,kYc0o/RIOT,aeneby/RIOT,gautric/RIOT,yogo1212/RIOT,altairpearl/RIOT,lazytech-org/RIOT,authmillenon/RIOT,ant9000/RIOT,tfar/RIOT,ks156/RIOT,miri64/RIOT,backenklee/RIOT,mtausig/RIOT,plushvoxel/RIOT,josephnoir/RIOT,jbeyerstedt/RIOT-OTA-update,immesys/RiSyn,thomaseichinger/RIOT,adrianghc/RIOT,beurdouche/RIOT,aeneby/RIOT,ant9000/RIOT,dailab/RIOT,mtausig/RIOT,rfuentess/RIOT,authmillenon/RIOT,beurdouche/RIOT,roberthartung/RIOT,LudwigOrtmann/RIOT,altairpearl/RIOT,OTAkeys/RIOT,adjih/RIOT,jasonatran/RIOT,backenklee/RIOT,kbumsik/RIOT,avmelnikoff/RIOT,kerneltask/RIOT,gebart/RIOT,cladmi/RIOT,OlegHahm/RIOT,cladmi/RIOT,hamilton-mote/RIOT-OS,OlegHahm/RIOT,mfrey/RIOT,adrianghc/RIOT,d00616/RIOT,smlng/RIOT,tfar/RIOT,LudwigOrtmann/RIOT,kaleb-himes/RIOT,adjih/RIOT,alignan/RIOT,beurdouche/RIOT,dkm/RIOT,syin2/RIOT,jfischer-phytec-iot/RIOT,authmillenon/RIOT,biboc/RIOT,hamilton-mote/RIOT-OS,lazytech-org/RIOT,neiljay/RIOT,jfischer-phytec-iot/RIOT,rfuentess/RIOT,OlegHahm/RIOT,x3ro/RIOT,yogo1212/RIOT,OlegHahm/RIOT,Josar/RIOT,basilfx/RIOT,kb2ma/RIOT,Hyungsin/RIOT-OS,x3ro/RIOT,backenklee/RIOT,jbeyerstedt/RIOT-OTA-update,BytesGalore/RIOT,beurdouche/RIOT,kb2ma/RIOT,roberthartung/RIOT,katezilla/RIOT,kaspar030/RIOT,Hyungsin/RIOT-OS,Hyungsin/RIOT-OS,gebart/RIOT,BytesGalore/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT,jasonatran/RIOT,mfrey/RIOT,ks156/RIOT,dailab/RIOT,kaleb-himes/RIOT,jfischer-phytec-iot/RIOT,gebart/RIOT,biboc/RIOT,Josar/RIOT,thomaseichinger/RIOT,toonst/RIOT,mfrey/RIOT,immesys/RiSyn,avmelnikoff/RIOT,katezilla/RIOT,gautric/RIOT,basilfx/RIOT,roberthartung/RIOT,cladmi/RIOT,jbeyerstedt/RIOT-OTA-update,BytesGalore/RIOT,ant9000/RIOT,TobiasFredersdorf/RIOT,jasonatran/RIOT,alignan/RIOT,miri64/RIOT,biboc/RIOT,altairpearl/RIOT,smlng/RIOT,katezilla/RIOT,jasonatran/RIOT,LudwigKnuepfer/RIOT,ks156/RIOT,mfrey/RIOT,dkm/RIOT,kb2ma/RIOT,BytesGalore/RIOT,LudwigOrtmann/RIOT,smlng/RIOT,thomaseichinger/RIOT,mtausig/RIOT,miri64/RIOT,jfischer-phytec-iot/RIOT,OTAkeys/RIOT,ant9000/RIOT,mtausig/RIOT,kaspar030/RIOT,plushvoxel/RIOT,plushvoxel/RIOT,d00616/RIOT,syin2/RIOT,Ell-i/RIOT,kaleb-himes/RIOT,dkm/RIOT,lazytech-org/RIOT,basilfx/RIOT,altairpearl/RIOT,dkm/RIOT,josephnoir/RIOT,backenklee/RIOT,yogo1212/RIOT,katezilla/RIOT,TobiasFredersdorf/RIOT,adjih/RIOT,authmillenon/RIOT,TobiasFredersdorf/RIOT,RIOT-OS/RIOT,tfar/RIOT,biboc/RIOT,Hyungsin/RIOT-OS,d00616/RIOT,gautric/RIOT,neumodisch/RIOT,avmelnikoff/RIOT,dkm/RIOT,yogo1212/RIOT,toonst/RIOT,mfrey/RIOT,jfischer-phytec-iot/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT,rfuentess/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,neiljay/RIOT,neumodisch/RIOT,TobiasFredersdorf/RIOT,rfuentess/RIOT,jbeyerstedt/RIOT-OTA-update,LudwigOrtmann/RIOT,yogo1212/RIOT,rfuentess/RIOT,mtausig/RIOT,miri64/RIOT,roberthartung/RIOT,Josar/RIOT,Josar/RIOT,LudwigKnuepfer/RIOT,backenklee/RIOT,x3ro/RIOT,BytesGalore/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,kYc0o/RIOT,x3ro/RIOT,adrianghc/RIOT,OTAkeys/RIOT,kerneltask/RIOT,roberthartung/RIOT,LudwigOrtmann/RIOT,gebart/RIOT,d00616/RIOT,LudwigKnuepfer/RIOT,altairpearl/RIOT,alignan/RIOT,OTAkeys/RIOT,smlng/RIOT,toonst/RIOT,neumodisch/RIOT,toonst/RIOT,yogo1212/RIOT,ant9000/RIOT,neiljay/RIOT,kerneltask/RIOT,kaspar030/RIOT,RIOT-OS/RIOT,gautric/RIOT,kerneltask/RIOT,neumodisch/RIOT,adjih/RIOT,Hyungsin/RIOT-OS,dailab/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT,LudwigKnuepfer/RIOT,alignan/RIOT,kb2ma/RIOT,neumodisch/RIOT,lazytech-org/RIOT,LudwigKnuepfer/RIOT,basilfx/RIOT,kbumsik/RIOT,basilfx/RIOT,neiljay/RIOT,neiljay/RIOT,kbumsik/RIOT,foss-for-synopsys-dwc-arc-processors/RIOT,syin2/RIOT,aeneby/RIOT,jbeyerstedt/RIOT-OTA-update,foss-for-synopsys-dwc-arc-processors/RIOT,gautric/RIOT,d00616/RIOT,kaspar030/RIOT,thomaseichinger/RIOT,A-Paul/RIOT,Ell-i/RIOT,hamilton-mote/RIOT-OS,plushvoxel/RIOT,Ell-i/RIOT,OlegHahm/RIOT,dailab/RIOT,gebart/RIOT,neumodisch/RIOT,kbumsik/RIOT,adjih/RIOT,beurdouche/RIOT,authmillenon/RIOT,TobiasFredersdorf/RIOT,kb2ma/RIOT,josephnoir/RIOT,A-Paul/RIOT,immesys/RiSyn,Josar/RIOT,kbumsik/RIOT,cladmi/RIOT,kYc0o/RIOT,syin2/RIOT,A-Paul/RIOT,aeneby/RIOT,OTAkeys/RIOT,immesys/RiSyn,thomaseichinger/RIOT,authmillenon/RIOT,ks156/RIOT,LudwigOrtmann/RIOT,josephnoir/RIOT,A-Paul/RIOT,smlng/RIOT,immesys/RiSyn,avmelnikoff/RIOT,d00616/RIOT,tfar/RIOT,avmelnikoff/RIOT,plushvoxel/RIOT,syin2/RIOT,kerneltask/RIOT,RIOT-OS/RIOT,alignan/RIOT,Ell-i/RIOT,biboc/RIOT,adrianghc/RIOT,tfar/RIOT,A-Paul/RIOT,immesys/RiSyn,toonst/RIOT,kaleb-himes/RIOT,ks156/RIOT,hamilton-mote/RIOT-OS,kYc0o/RIOT,dailab/RIOT,Ell-i/RIOT,kYc0o/RIOT,katezilla/RIOT,lazytech-org/RIOT,miri64/RIOT,hamilton-mote/RIOT-OS