Made SAM adapters final.

compiler/testData/diagnostics/tests/j+k/cantDeclareIfSamAdapterIsInherited.kt

@@ -0,0 +1,17 @@
+// FILE: Super.java
+class Super {
+    void foo(Runnable r) {
+    }
+}
+
+// FILE: Sub.kt
+class Sub1() : Super() {
+    <!VIRTUAL_MEMBER_HIDDEN!>fun foo(r : (() -> Unit)?)<!> {
+    }
+}
+
+class Sub2() : Super() {
+    <!OVERRIDING_FINAL_MEMBER!>override<!> fun foo(r : (() -> Unit)?) {
+    }
+}
+