acl-plugin: split (L3) and (L4/pkt) logic of creation of 5tuple structure, optimize...

acl-plugin: split (L3) and (L4/pkt) logic of creation of 5tuple structure, optimize stores in the (l4/pkt)

Having two pieces of code - one for now much simpler to recreate L3 info,
one for a more difficult do build L4/pkt metadata allows more
degrees of freedom for optimizations.

Also, construct the metadata in local variables first before
saving it into the memory structure, this fewer memory stores
and they are better aligned, allowing to coalesce with
subsequent reads if needed.

Change-Id: Icb35d933834b14294f875362c9b58db3feb38d99
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>