kdbus.h: we don't need a size field in kdbus_manager_msg_name_change, since kdbus_msg_data includes that anyway
kdbus.h: let's make STARTER a flag of the connection rather than the well-known name
kdbus.h: we don't need both cookie_reply and timeout in the same message, so overload it
kdbus.h: fix tabs
kdbus.h: add KDBUS_CMD_NAME_STEAL_MESSAGES
kdbus.h: clarify that starter is a state of its own
catch up with interface changes
use KDBUS_(K)MSG_HEADER_SIZE
fix wrong substitution
TODO: update
kdbus.h: do not enforce limits in the API, we can do that in the code
message: pass kmsg pointer-ref to kdbus_kmsg_send()

kdbus_kmsg_send() will alter the actual memory backing the message, so
the caller will double-free.
message: refactor kdbus_kmsg_append_data to avoid one extra kmalloc()
message: cleanups
introduce kdbus_size_user() macro and use memdup_user() when possible
fix comments
message: augment with creds
test: dump creds as decimal
connection: use do_div() for 64-bit divisions
message: implement kdbus_msg_reply_dead()