pidl: Handle obtaining objects from a fixed-size array

pidl: Handle obtaining objects from a fixed-size array

Previously we would assume the array head was the talloc context
however this is not the case if the array is a fixed size inline array
within the parent struct.

In that case the overall object's talloc context is the correct
context to reference.

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Pair-programmed-with: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Noel Power <npower@samba.org>
Autobuild-User(master): Noel Power <npower@samba.org>
Autobuild-Date(master): Thu Nov 14 17:36:49 UTC 2019 on sn-devel-184