re PR middle-end/17657 (ICE in expand_case)

re PR middle-end/17657 (ICE in expand_case)

	PR middle-end/17657
	* stmt.c (add_case_node): Add additional type argument.  Declare
	as static to match prototype.  Convert the upper and lower bounds
	to the specified index type.  Optimize away case ranges/values
	that are outside the index type's bounds.  Truncate case ranges
	that span the index type's bounds.
	(expand_case): Avoid unnessary computation and memory allocation
	when index type is error_mark_node.  Pass index_type as required
	by change to add_case_node API.  No need to convert case range
	bounds to index_type, this is now done by add_case_node.

	* gcc.dg/switch-4.c: New test case.

From-SVN: r88881