Support equals/hashCode for fun interfaces in JVM and JVM_IR

#KT-33455 Fixed

libraries/stdlib/jvm/runtime/kotlin/jvm/internal/FunctionAdapter.java

@@ -0,0 +1,15 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package kotlin.jvm.internal;
+
+import kotlin.Function;
+import kotlin.SinceKotlin;
+
+@SuppressWarnings("unused")
+@SinceKotlin(version = "1.4")
+public interface FunctionAdapter {
+    Function<?> getFunctionDelegate();
+}