api: packet: add support for packet references
api: packet: add support for packet references

Introduce new APIs that support efficient sharing of portions of
packets:
 * odp_packet_ref_static() creates a new static reference
   for a packet
 * odp_packet_ref() creates a new dynamic reference to a packet
 * odp_packet_ref_pkt() creates a reference to a packet with
   a supplied header packet
 * odp_packet_has_ref() checks if a packet has multiple
   references to it
 * odp_packet_unshared_len() returns the unshared data length of
   a reference

Signed-off-by: Petri Savolainen <d528fd253b9aaf78fa72edbcc6249e82047f6ce6@nokia.com>
Signed-off-by: Bill Fischofer <52f3c909d51cc5d355a68a403df6906b3c1a8f83@linaro.org>
Reviewed-by: Balasubramanian Manoharan <affd9aba178b6c6e9aaff69252817fd03d71ae35@linaro.org>
Signed-off-by: Maxim Uvarov <db4d16e02ae2d7493db430203537da8b2e34f290@linaro.org>

erachmi/odp,erachmi/odp,erachmi/odp,erachmi/odp