[PATCH] PR14841 and PR15838

[Richard Kenner]

	* tree-ssa-ccp.c (try_extract_const_array_ref): New function to
	extract a constant from a constant array initializer.
	(try_extract_const_component_ref): Likewise for const struct
	initializers.
	(evaluate_stmt): Use them.

We're duplicating a lot of code from fold-const.c.