Generate INVOKESPECIAL instruction for private method with default argument

compiler/testData/codegen/functions/privateDefaultArgs.kt

@@ -0,0 +1,13 @@
+// Check that this code doesn't contains INVOKEVIRTUAL instruction
+class B {
+    private fun foo(i: Int = 1) {
+    }
+
+    fun f() {
+       foo(2)
+    }
+}
+
+fun box(): String {
+    return "OK"
+}