re PR tree-optimization/78819 (Wrong code with VRP caused by register assertions along default switch labels)

	PR tree-optimization/78819
	* tree-vrp.c (find_switch_asserts): Return if the insertion limit is 0.
	Don't register an assertion if the default case shares a label with
	another case.

	* gcc.dg/tree-ssa/vrp112.c: New test.

From-SVN: r243746