It appears that this issue has been raised here but has not yet been resolved: Error while building rtems-libbsd
There is no need to copy 7/ to cr12/ as this is a reference to the RTEMS version and you are unlikely to be making changes to the RTEMS 7 toolchain definitions. There is also no need to copy bare/ to cr12/ or even to copy pc.bset to cr12.bset. Is there a guide that you’re following that suggested this?