Add a structure that only contains IP header fields to be used by
functions that don't need UDP
Rename IP_HDR_SIZE_NO_UDP to IP_HDR_SIZE
Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Rename IP header related things to IP_UDP. The existing definition
of IP_t includes UDP header, so name it to accurately describe the
structure.
Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>