client convert to new headers scheme eliminating mallocs

client convert to new headers scheme eliminating mallocs

This removes all the direct wsi members specific to clients,
most of them are moved to being fake headers in the next 3-layer
header scheme, c_port moves to being a member of the u.hdr
unionized struct.

It gets rid of a lot of fiddly mallocs and frees(), despite it
adds a small internal API to create the fake headers, actually
the patch deletes more than it adds...

Signed-off-by: Andy Green <andy.green@linaro.org>