Check that boxing instruction is simple call

like T.valueOf(unboxType(T))

 #KT-6047 fixed

compiler/testData/codegen/boxWithStdlib/boxingOptimization/kt6047.kt

@@ -0,0 +1,18 @@
+import kotlin.test.assertEquals
+
+fun checkLongAB5E(x: Long) = assertEquals(0xAB5EL, x)
+fun checkDouble1(y: Double) = assertEquals(1.0, y)
+fun checkByte10(z: Byte) = assertEquals(10.toByte(), z)
+
+fun box(): String {
+    val x = java.lang.Long.valueOf("AB5E", 16)
+    checkLongAB5E(x)
+
+    val y = java.lang.Double.valueOf("1.0")
+    checkDouble1(y)
+
+    val z = java.lang.Byte.valueOf("A", 16)
+    checkByte10(z)
+
+    return "OK"
+}