The configure script checks for ipset v6 availability but doesn't test
for v7, which is backward compatible and used on kernel v5.x systems.
Update the script to test for both ipset versions. Without this change,
the tc ematch function em_ipset will be disabled.

Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>