Fix KotlinReflectionInternalError on encountering 'clone' in a class

`RuntimeTypeMapper.mapSignature` threw exception because the descriptor
for `clone` was created manually in CloneableClassScope and therefore it
didn't have a JVM signature as in deserialized descriptors, and wasn't
recognized as a Java method either.

 #KT-22923 Fixed

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

@@ -30,8 +30,7 @@ fun box(): String {
         MyCustomMembers::class.functions()
     )
 
-    // TODO: KT-22923
-    // assertEquals(listOf("clone", "equals", "hashCode", "toString"), MyCloneable::class.functions())
+    assertEquals(listOf("clone", "equals", "hashCode", "toString"), MyCloneable::class.functions())
 
     return "OK"
 }