traceroute: update to 2.0.21

Also fix LICENSE to be "or any later version" (as specified in the
upstream source headers); both licenses apply so use &.

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Joe MacDonald <joe_macdonald@mentor.com>