Update ICU to 58.1

source/i18n/unicode/rbnf.h

Index: source/i18n/unicode/rbnf.h
diff --git a/source/i18n/unicode/rbnf.h b/source/i18n/unicode/rbnf.h
index 8d619862f2aa990da8ea339d98bc832bbe2627e1..d41ffbe3816a67b5c41fa79d82f372c02b326af3 100644
--- a/source/i18n/unicode/rbnf.h
+++ b/source/i18n/unicode/rbnf.h
@@ -1,3 +1,5 @@
+// Copyright (C) 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
 /*
 *******************************************************************************
 * Copyright (C) 1997-2015, International Business Machines Corporation and others.
@@ -54,7 +56,13 @@ enum URBNFRuleSetTag {
     URBNF_ORDINAL,
     URBNF_DURATION,
     URBNF_NUMBERING_SYSTEM,
+#ifndef U_HIDE_DEPRECATED_API
+    /**
+     * One more than the highest normal URBNFRuleSetTag value.
+     * @deprecated ICU 58 The numeric value may change over time, see ICU ticket #12420.
+     */
     URBNF_COUNT
+#endif  // U_HIDE_DEPRECATED_API
 };
 
 /**