[lwip-members] removed, then added back pack directives

[Leon Woestenberg]

Just to be sure everyone is on to this:

I have removed the pack directives from HEAD recently.

More recently, I added them back, because  *nested structs*
in a protocol headers struct get 4-byte alignment on arm-gcc
compilers, *regardless* of alignment constraints of the first
field.

Sometimes, this will create a 2-byte hole between
the headers of different protocols.

So, ignore my request to have pack directives removed.
I already tried it and it did not work.

Regards,

Leon.