examples: add extern "C" to header `rpl_udp.h`
examples: add extern "C" to header `rpl_udp.h`

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