3650 mdb global symbol tab completion should find all symbols
3651 mdb_readsym() and friends should find all symbols
3652 convert ::spa and ::spa_vdevs to use mdb_ctf_vread()
3653 userland ::whatis always complains about "umem_internal_arena" symbol
Reviewed by: Henrik Mattson <henrik.mattson@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Approved by: Dan McDonald <danmcd@nexenta.com>