dist/tools/edbg: Clear environment before building edbg
dist/tools/edbg: Clear environment before building edbg

This fixes compilation on macOS. Without this, autoconf
might pick up INCLUDES and LINKER variables causing compilation
and linking errors.

LudwigOrtmann/RIOT,x3ro/RIOT,toonst/RIOT,ks156/RIOT,aeneby/RIOT,RIOT-OS/RIOT,miri64/RIOT,roberthartung/RIOT,LudwigOrtmann/RIOT,kbumsik/RIOT,adrianghc/RIOT,yogo1212/RIOT,kaspar030/RIOT,josephnoir/RIOT,gebart/RIOT,immesys/RiSyn,neiljay/RIOT,authmillenon/RIOT,mtausig/RIOT,aeneby/RIOT,josephnoir/RIOT,toonst/RIOT,rfuentess/RIOT,Josar/RIOT,LudwigKnuepfer/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,authmillenon/RIOT,OlegHahm/RIOT,basilfx/RIOT,cladmi/RIOT,lazytech-org/RIOT,ks156/RIOT,jasonatran/RIOT,Josar/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,basilfx/RIOT,roberthartung/RIOT,adrianghc/RIOT,LudwigOrtmann/RIOT,ks156/RIOT,mfrey/RIOT,rfuentess/RIOT,cladmi/RIOT,rfuentess/RIOT,miri64/RIOT,biboc/RIOT,jasonatran/RIOT,LudwigKnuepfer/RIOT,OlegHahm/RIOT,neiljay/RIOT,immesys/RiSyn,ant9000/RIOT,ks156/RIOT,basilfx/RIOT,roberthartung/RIOT,immesys/RiSyn,x3ro/RIOT,toonst/RIOT,ant9000/RIOT,lazytech-org/RIOT,josephnoir/RIOT,biboc/RIOT,mtausig/RIOT,Josar/RIOT,LudwigKnuepfer/RIOT,kYc0o/RIOT,smlng/RIOT,lazytech-org/RIOT,roberthartung/RIOT,avmelnikoff/RIOT,mtausig/RIOT,cladmi/RIOT,LudwigOrtmann/RIOT,mtausig/RIOT,kYc0o/RIOT,mfrey/RIOT,LudwigOrtmann/RIOT,mfrey/RIOT,avmelnikoff/RIOT,kbumsik/RIOT,neiljay/RIOT,toonst/RIOT,rfuentess/RIOT,x3ro/RIOT,jasonatran/RIOT,LudwigOrtmann/RIOT,avmelnikoff/RIOT,smlng/RIOT,kaspar030/RIOT,miri64/RIOT,mfrey/RIOT,A-Paul/RIOT,kbumsik/RIOT,adrianghc/RIOT,BytesGalore/RIOT,adrianghc/RIOT,lazytech-org/RIOT,OlegHahm/RIOT,kYc0o/RIOT,Josar/RIOT,miri64/RIOT,ant9000/RIOT,gebart/RIOT,RIOT-OS/RIOT,gebart/RIOT,kbumsik/RIOT,rfuentess/RIOT,kaspar030/RIOT,yogo1212/RIOT,kaspar030/RIOT,smlng/RIOT,authmillenon/RIOT,OlegHahm/RIOT,miri64/RIOT,ant9000/RIOT,Josar/RIOT,cladmi/RIOT,BytesGalore/RIOT,A-Paul/RIOT,OTAkeys/RIOT,gebart/RIOT,yogo1212/RIOT,LudwigKnuepfer/RIOT,mfrey/RIOT,kbumsik/RIOT,BytesGalore/RIOT,A-Paul/RIOT,OTAkeys/RIOT,x3ro/RIOT,ant9000/RIOT,x3ro/RIOT,kaspar030/RIOT,authmillenon/RIOT,biboc/RIOT,aeneby/RIOT,aeneby/RIOT,ks156/RIOT,avmelnikoff/RIOT,yogo1212/RIOT,LudwigKnuepfer/RIOT,jasonatran/RIOT,josephnoir/RIOT,basilfx/RIOT,adrianghc/RIOT,neiljay/RIOT,A-Paul/RIOT,smlng/RIOT,A-Paul/RIOT,toonst/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,gebart/RIOT,lazytech-org/RIOT,kYc0o/RIOT,BytesGalore/RIOT,OTAkeys/RIOT,cladmi/RIOT,mtausig/RIOT,yogo1212/RIOT,biboc/RIOT,biboc/RIOT,roberthartung/RIOT,BytesGalore/RIOT,OlegHahm/RIOT,yogo1212/RIOT,immesys/RiSyn,immesys/RiSyn,smlng/RIOT,neiljay/RIOT,OTAkeys/RIOT,josephnoir/RIOT,basilfx/RIOT,aeneby/RIOT,avmelnikoff/RIOT,immesys/RiSyn