jiminy-mega256rfr2: add `BOOTLOADER_CLEARS_WATCHDOG_AND_PASSES_MCUSR`
jiminy-mega256rfr2: add `BOOTLOADER_CLEARS_WATCHDOG_AND_PASSES_MCUSR`

This variable helps to inform at boot time that some
information about the booting process, e.g. reset cause.

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