Remove use of local stack variables (size, ptr) for {PORTAL,OBD}_{ALLOC,FREE}().

Remove use of local stack variables (size, ptr) for {PORTAL,OBD}_{ALLOC,FREE}().
I think these were intended to avoid doing multiple evals of math/function
calls for the size, but all of our usage so far is passing in a constant
or a variable that has already computed the size.

By reordering the *_FREE() macros slightly, we do not need to store the size
of the free in a local stack variable either.  We have to be careful though,
because "size" may be part of the struct we are poisoning/freeing.