re PR tree-optimization/49161 (Fix VRP on switch stmts)

re PR tree-optimization/49161 (Fix VRP on switch stmts)

	PR tree-optimization/49161
	* tree-vrp.c (struct case_info): New type.
	(compare_case_labels): Sort case_info structs instead of
	trees, and not primarily by CASE_LABEL uids but by
	label_for_block indexes.
	(find_switch_asserts): Put case labels into struct case_info
	array instead of TREE_VEC, adjust sorting, compare label_for_block
	values instead of CASE_LABELs.

	* gcc.c-torture/execute/pr49161.c: New test.

From-SVN: r174270