Support variable length blobs in RPC

[Daniel Waddington]

Hi,
What's the best way to create RPC types for variable length data
(assuming a maximum size of that will fit in the UTCB).  I looked at
Rpc_in_buffer, but this seems to only support strings, and using as an
out param seems awkward.  For the moment I am using a statically sized
structure, but I fear there is needless copying going on.  BTW, this RPC
is for one-off control - of course shared memory is better for
streaming.

Daniel