address of the head, not to the head itself. Not sure if the cast of the
arg to db_value_name() is right, but works on i386 and compiles on sparc64.
Stack traces from ddb work again on i386.
types of changes:
- Add a few new methods to replace stuff like p_find(), CPU_INFO_FOREACH.
- Use db_read_bytes() instead of accessing kernel structures directly,
and similar changes.
- Add ifdef _KERNEL where the above hasn't been done, and an XXX comment.
