scsi_debug: switch to table based parser

This series of patches is in response to Hannes' comments earlier today. He wanted the single large patch broken up.

Changes since v1:
- break single big patch into 4 smaller ones and one less large
- resync with drivers-for-3.19

Patches:
[PATCH v2 1/5] pinpoint invalid field in sense data [PATCH v2 2/5] append inject error flags onto scsi_cmnd object [PATCH v2 3/5] add Capacity Changed Unit Attention [PATCH v2 4/5] change SCSI command parser to table driven [PATCH v2 5/5] Add Report supported opcodes+tmfs; Compare and write

Todo:
- re-order teardown in scsi_debug_exit()
- make sdebug_dev_info::stopped atomic (add to end of uas_bm ?)
- review Rob Elliott's suggestions; look at speed ups
- remove host_lock logic and make the host_lock option a dummy
- update some mode page and VPD data to reflect more recent devices
- changing remaining >> and << byte handling over to

     get/put_unaligned_be*()

- set INFO field for COMPARE AND WRITE command MISCOMPAREs

Hannes also asked that XDWRITEREAD_10 be added to scsi.h . It has been there for a while. I guess he meant something else.

Thanks, applied the whole series to drivers-for-3.19. I also switched it to use the symbolic constant as pointed out by Hannes.