(output_init_element): When putting an elt into a
CONSTRUCTOR, always set the TREE_PURPOSE (even for arrays).
Copy the node if it's an INTEGER_CST.
(output_pending_init_elements): If have gap and not incremental,
advance constructor_unfilled_fields or constructor_unfilled_index.

(push_init_level): Pop any implicit levels
that have been filled up.
Don't die if constructor_type is 0.
(process_init_element): If VALUE is 0 for union type,
update constructor_bit_index.

From-SVN: r5317