Devirtualization fails to eliminate boxing in function reference context

^KT-49847 Fixed

Merge-request: KT-MR-6460
Merged-by: Vladimir Sukharev <Vladimir.Sukharev@jetbrains.com>

kotlin-native/backend.native/tests/filecheck/kt49847_simple_function_reference.kt

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2010-2022 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.
+ */
+
+fun plus1(x: Int) = x + 1
+
+// CHECK: define void @"kfun:#main(){}"()
+// CHECK-NOT: Int-box
+// CHECK-NOT: Int-unbox
+// CHECK: ret void
+fun main() {
+    val ref = ::plus1
+    var y = 0
+    repeat(100000) {
+        y += ref(it)  // Should be devirtualized and invoked without boxing/unboxing (`Int-box`/`Int-unbox`)
+    }
+    if (y > 999999)
+        println("y > 999999")
+}