r9373: - create a hierachical memory tree with recursiv ndr_pull_* functions

r9373: - create a hierachical memory tree with recursiv ndr_pull_* functions
- with this it's also possible to talloc_free() the ndr_pull structure
  and talloc_steal(ndr->current_mem_ctx); to fetch the whole data of the hierachical tree
- if the toplevel struct is a valid talloc pointer it's also possible to use
  NDR_PULL_SET_MEM_CTX(ndr, mem_ctx); to the the toplevel pointer with the struct pointer

(NOTE: no callers are using this yet, but they shortly will)

metze
(This used to be commit 1a2b8369586642cc9bc15d015c1e4256c3a92732)