reverted jeremy's c++-like security descriptor modifications as the

reverted jeremy's c++-like security descriptor modifications as the
simplest method to get rpcclient's reggetsec command working.  the
buffers passed as arguments in do_reg_get_key_sec() do need to be
locally allocated not dynamically allocated, as two calls to
reg_get_key_sec() are needed.  on the first, the server fills in the
size of the security descriptor buffer needed.  on the second, the
server fills in the security descriptor buffer.
(This used to be commit b2d9cbef6f65bb696df8d8f49aa0c240e0bb1f50)