We need to be careful to avoid infinite recursion in recursive vet checks that consider type parameters. The following code causes an infinite recursion in the new copylock logic (discovered when gopls crashed while working on similar handling for infinite recursion in the printf analyzer...).

func TestRecursiveTypeParams[T1 ~[]T2, T2 ~[]T1 | string, T3 ~struct{ F T3 }](t1 T1, t2 T2, t3 T3) {
}

I'll audit the other updated vet analyzers for similar problems.

CC @timothy-king