cortexm_common_ldscript: add test for linker script offset
cortexm_common_ldscript: add test for linker script offset

Compile two elf files with different offset and verify the linked file offset.
I only enabled samr21-xpro and iotlab nodes for the moment.

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