Don't generate unnecessary accessors for private class properties

compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/privateClassPropertyNoClash.kt

@@ -0,0 +1,13 @@
+// FILE: A.java
+
+public class A {
+    public String getFoo() {
+        return "Foo";
+    }
+}
+
+// FILE: B.kt
+
+class B(private val foo: String) : A() {
+    override fun getFoo(): String = foo
+}