tests: print missing thread_t attribute
tests: print missing thread_t attribute

This adds the `stack_size` attribute which wasn't printed right now
so for instance the numbers didn't add for the sizeof(thread_t) when
DEVELHELP was on its of by 4 bytes (on 32-Bit).

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