xenstore: call each xenstored command function with temporary context

xenstore: call each xenstored command function with temporary context

In order to be able to avoid leaving temporary memory allocated after
processing of a command in xenstored call all command functions with
the temporary "in" context. Each function can then make use of that
temporary context for allocating temporary memory instead of either
leaving that memory allocated until the connection is dropped (or
even until end of xenstored) or freeing the memory itself.

This requires to modify the interfaces of the functions taking only
one argument from the connection by moving the call of onearg() into
the single functions. Other than that no functional change.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>