Supported SAM constructors in codegen (simplest case).

compiler/testData/codegen/box/sam/runnableAccessingClosure1.kt

@@ -0,0 +1,8 @@
+fun box(): String {
+    val o = "O"
+    var result = ""
+
+    val r = Runnable { result = o + "K" } //capturing local vals and local var
+    r.run()
+    return result
+}