Fixes#3187
Requires seastar "inet_address: Add constructor and conversion function
from/to IPv4"
Implements support IPv6 for CQL inet data. The actual data stored will
now vary between 4 and 16 bytes. gms::inet_address has been augumented
to interop with seastar::inet_address, though of course actually trying
to use an Ipv6 address there or in any of its tables with throw badly.
Tests assuming ipv4 changed. Storing a ipv4_address should be
transparent, as it now "widens". However, since all ipv4 is
inet_address, but not vice versa, there is no implicit overloading on
the read paths. I.e. tests and system_keyspace (where we read ip
addresses from tables explicitly) are modified to use the proper type.
Message-Id: <20180424161817.26316-1-calle@scylladb.com>
b1edf75c8b