FIR: bail out early for override check if base candidate is private

compiler/testData/codegen/box/properties/privatePropertyInConstructor.kt

@@ -1,10 +1,11 @@
-class A(
-        private val x: String,
-        private var y: Double
+open class A(
+    private val x: String,
+    private var y: Double
 ) {
     fun foo() {
         val r = {
             if (x != "abc") throw AssertionError("$x")
+            if (y < 0.0) throw AssertionError("$y < 0.0")
             y = 0.0
             if (y != 0.0) throw AssertionError("$y")
         }
@@ -12,7 +13,14 @@ class A(
     }
 }
 
+class B(
+    val x: String,
+    y: Double
+) : A("abc", y)
+
 fun box(): String {
     A("abc", 3.14).foo()
-    return "OK"
+    val b = B("OK", 0.42)
+    b.foo()
+    return b.x
 }