Quiet some clang warnings when compiling CTL.

ctl_error.c,
ctl_error.h: Take out the ctl_sense_format enumeration, and use

		scsi_sense_data_type instead.

		Remove ctl_get_sense_format() and switch ctl_build_ua()
		over to using scsi_sense_data_type.

ctl_backend_ramdisk.c,
ctl_backend_block.c:

		Use C99 structure initializers instead of GNU initializers.

ctl.c: Switch over to using the SCSI sense format enumeration

		instead of the CTL-specific enumeration.

Submitted by: dim (partially)
MFC after: 1 month