Add basic stubs and files to build the new or1k BSP: or1ksim.
This is not meant to be upstreamed, it's just some trials that may
help, in the time being, in debugging bare-metal applications and minimal
basic infrastructure for or1k architecture. However, it can be
a starting point when moving to RTEMS porting task.
The following are major changes:

+cpukit/cpu: added or1k cpu, some files are borrowed and modified
from the old or32 port. Stubs, definitions and changes made to be
able to build libraries and move to bsp.

+libbsp/or1k: Minimal configuration for adding new or1k/or1ksim
BSP. This bsp only has start.S which do nothing other than calling
main. It's provided to make sure that libbsp.a is generated when
building RTEMS for or1k.