portability updates

add check if ipv6/sockaddr_in6 is availavble or not
add check for poll.h and only include when available
add includes for AROS
Add support for AROS
ISCSI-LS : Change from popt to the slightly less portable getopt_long

win32 and amiga/aros does not have getopt_long() so we will need a
replacement for the platforms where getopt_long() is missing.
ISCSI-INQ:  convert to getopt_long instead of popt
ISCSI-READCAPACITY16  convert to getopt_long()
convert iscsi-dd to use getopt_long()
iscsi-support.c does not need popt.h
covnert the old test suite grom popt to getopt_long
Get rid of the popt dependency
Add handling of inquiry version descriptors
Add a test for mandatory opcodes for SBC devices.

Note that Read16/Readcapacity16 are mandatory on SBC3 but not prior.
Not all mandatory opcodes are tested for yet.
TESTS: make the "is readcapacity16 supported on this device" tests cleaner
TESTS update all read16 tests to fail/skip on illegal opcode depending on whether the device claims support for it or not (mandatory in sbc-3, optional prior)
fix typo
Add SSC to the version descriptors.
I actually have a usb-stick that claims it supports SSC. I stongly doubt it.
missing ,   broke compile
Revert "Add SSC to the version descriptors."

This reverts commit 45f5fc21056c7843559d4d839913698e1e57ee3c.

Conflicts:

	include/scsi-lowlevel.h
add missing version descriptor
AROS: We need emulation of readv/writev on aros
Create safe 16/32/64 bit accessors for reading from the datain buffer
and use it throughout the scsi lowlevel file.

We probably want a safe accessor for byte access to at some stage.