Unwrap fake override of original

This fixes a couple of verify errors related to the order of supertypes in the
class declaration

compiler/testData/codegen/box/fakeOverride/diamondFunction.kt

@@ -0,0 +1,31 @@
+trait T {
+    fun foo(): Unit
+}
+
+open class A : T {
+    override fun foo() {}
+}
+
+trait B : T
+
+class C : A(), B
+class D : B, A()
+class E : A(), B, T
+class F : B, A(), T
+class G : A(), T, B
+class H : B, T, A()
+class I : T, A(), B
+class J : T, B, A()
+
+fun box(): String {
+    C().foo()
+    D().foo()
+    E().foo()
+    F().foo()
+    G().foo()
+    H().foo()
+    I().foo()
+    J().foo()
+
+    return "OK"
+}