tree-sra.c (struct sra_walk_fns): Init function now returns bool.

	* tree-sra.c (struct sra_walk_fns): Init function now returns bool.
	(sra_walk_modify_expr): Allow init function to fail.
	(scan_init): Now returns bool.
	(generate_element_init): If can't understand INIT, return false.
	(scalarize_init): Return false if generate_element_init does.

From-SVN: r84120