ubsan: Fix up another spot that should have been BUILT_IN_UNREACHABLE_TRAPS [PR108655]

ubsan: Fix up another spot that should have been BUILT_IN_UNREACHABLE_TRAPS [PR108655]

We ICE on the following testcase, because ivcanon calls
gimple_build_builtin_unreachable but doesn't expect it would need vops.
BUILT_IN_UNREACHABLE_TRAP I've introduced yesterday doesn't need
vops and should be used in that case instead of BUILT_IN_TRAP which
needs them.

2023-02-06  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/108655
	* ubsan.cc (sanitize_unreachable_fn): For -funreachable-traps
	or -fsanitize=unreachable -fsanitize-trap=unreachable return
	BUILT_IN_UNREACHABLE_TRAP decl rather than BUILT_IN_TRAP.

	* gcc.dg/pr108655.c: New test.