libwebsockets

refactor-struct-lws-hdr

Migrate what used to be in lws_hdr_related into either the ah
or the wsi, and eliminate it along with the three different ways
used to access things inside it.

Eg wsi->u.hdr.ah and wsi->u.http.ah become wsi->ah

These changes are internal-only, in private-libwebsockets.h and lib.