'when' should use intrinsics for '=='

#KT-19029 Fixed Target versions 1.1.5
 #KT-18818 Fixed Target versions 1.1.5

compiler/testData/codegen/bytecodeText/when/kt18818.kt

@@ -0,0 +1,14 @@
+// WITH_RUNTIME
+
+fun findUserId(username: String): Long? = null
+
+fun main(args: Array<String>) {
+    val userId = findUserId("abcd")
+
+    when (userId) {
+        null -> println("User not found")
+        else -> println("User ID: $userId")
+    }
+}
+
+// 0 areEqual