makefiles/scan-build: make RIOT_CI_BUILD visible to scan-build
makefiles/scan-build: make RIOT_CI_BUILD visible to scan-build

This is required to have reference builds context using the right
RIOT_VERSION_OVERRIDE=buildtest.

basilfx/RIOT,authmillenon/RIOT,miri64/RIOT,cladmi/RIOT,RIOT-OS/RIOT,x3ro/RIOT,cladmi/RIOT,ant9000/RIOT,aeneby/RIOT,yogo1212/RIOT,basilfx/RIOT,lazytech-org/RIOT,miri64/RIOT,OTAkeys/RIOT,RIOT-OS/RIOT,miri64/RIOT,gebart/RIOT,BytesGalore/RIOT,OlegHahm/RIOT,yogo1212/RIOT,basilfx/RIOT,toonst/RIOT,kaspar030/RIOT,authmillenon/RIOT,josephnoir/RIOT,lazytech-org/RIOT,yogo1212/RIOT,mtausig/RIOT,jasonatran/RIOT,A-Paul/RIOT,mtausig/RIOT,A-Paul/RIOT,OTAkeys/RIOT,ant9000/RIOT,lazytech-org/RIOT,smlng/RIOT,aeneby/RIOT,smlng/RIOT,gebart/RIOT,authmillenon/RIOT,smlng/RIOT,jasonatran/RIOT,OlegHahm/RIOT,rfuentess/RIOT,mtausig/RIOT,rfuentess/RIOT,jasonatran/RIOT,rfuentess/RIOT,basilfx/RIOT,josephnoir/RIOT,kYc0o/RIOT,A-Paul/RIOT,rfuentess/RIOT,kYc0o/RIOT,kaspar030/RIOT,mfrey/RIOT,rfuentess/RIOT,jasonatran/RIOT,toonst/RIOT,kYc0o/RIOT,biboc/RIOT,authmillenon/RIOT,x3ro/RIOT,lazytech-org/RIOT,ant9000/RIOT,BytesGalore/RIOT,yogo1212/RIOT,gebart/RIOT,cladmi/RIOT,RIOT-OS/RIOT,smlng/RIOT,BytesGalore/RIOT,yogo1212/RIOT,OlegHahm/RIOT,josephnoir/RIOT,mtausig/RIOT,toonst/RIOT,toonst/RIOT,RIOT-OS/RIOT,josephnoir/RIOT,miri64/RIOT,kaspar030/RIOT,aeneby/RIOT,smlng/RIOT,A-Paul/RIOT,kYc0o/RIOT,mfrey/RIOT,basilfx/RIOT,x3ro/RIOT,jasonatran/RIOT,biboc/RIOT,biboc/RIOT,authmillenon/RIOT,kaspar030/RIOT,mfrey/RIOT,aeneby/RIOT,RIOT-OS/RIOT,biboc/RIOT,biboc/RIOT,aeneby/RIOT,mfrey/RIOT,ant9000/RIOT,mfrey/RIOT,OTAkeys/RIOT,cladmi/RIOT,x3ro/RIOT,gebart/RIOT,x3ro/RIOT,BytesGalore/RIOT,OlegHahm/RIOT,cladmi/RIOT,miri64/RIOT,yogo1212/RIOT,lazytech-org/RIOT,authmillenon/RIOT,OlegHahm/RIOT,gebart/RIOT,BytesGalore/RIOT,kYc0o/RIOT,toonst/RIOT,A-Paul/RIOT,josephnoir/RIOT,mtausig/RIOT,OTAkeys/RIOT,OTAkeys/RIOT,ant9000/RIOT,kaspar030/RIOT