Fix access to private static native functions

compiler/testData/codegen/boxWithStdlib/platformStatic/privateMethod.kt

@@ -0,0 +1,16 @@
+import kotlin.platform.platformStatic
+
+object A {
+
+    private platformStatic fun a(): String {
+        return "OK"
+    }
+
+    object Z {
+        val p = a()
+    }
+}
+
+fun box(): String {
+    return A.Z.p
+}