Fix regression in reflection on looking up equals/hashCode/toString in interface

Caused by 4266e50be8 and 8ccbbf71ec. Previously it worked because we
used hardcoded signatures of equals/hashCode/toString and always looked
them up in java.lang.Object

 #KT-25404 Fixed

compiler/testData/codegen/box/reflection/mapping/methodsFromObject.kt

@@ -0,0 +1,37 @@
+// TARGET_BACKEND: JVM
+// WITH_REFLECT
+
+import kotlin.reflect.KClass
+import kotlin.reflect.full.memberFunctions
+import kotlin.reflect.jvm.javaMethod
+import kotlin.test.assertEquals
+
+annotation class A
+interface I
+class C
+
+interface MyCustomMembers {
+    fun equals(): Boolean
+    fun hashCode(hehe: Int): Int
+    fun toString(hehe: String): Any
+}
+
+interface MyCloneable : Cloneable
+
+fun KClass<*>.functions() = memberFunctions.map { it.javaMethod!!.name }.sorted()
+
+fun box(): String {
+    assertEquals(listOf("equals", "hashCode", "toString"), A::class.functions())
+    assertEquals(listOf("equals", "hashCode", "toString"), I::class.functions())
+    assertEquals(listOf("equals", "hashCode", "toString"), C::class.functions())
+
+    assertEquals(
+        listOf("equals", "equals", "hashCode", "hashCode", "toString", "toString"),
+        MyCustomMembers::class.functions()
+    )
+
+    // TODO: KT-22923
+    // assertEquals(listOf("clone", "equals", "hashCode", "toString"), MyCloneable::class.functions())
+
+    return "OK"
+}