Update ICU to 58.1

source/common/unicode/udata.h

Index: source/common/unicode/udata.h
diff --git a/source/common/unicode/udata.h b/source/common/unicode/udata.h
index 29e46630d5398d82738d1d61ffc4d2c914e8c68b..bde719d8e2e2712c942f9513da317f2e7e548555 100644
--- a/source/common/unicode/udata.h
+++ b/source/common/unicode/udata.h
@@ -1,3 +1,5 @@
+// Copyright (C) 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
 /*
 ******************************************************************************
 *
@@ -408,8 +410,13 @@ typedef enum UDataFileAccess {
     UDATA_PACKAGES_FIRST,
     /** ICU does not access the file system for data loading. @stable ICU 3.4 */
     UDATA_NO_FILES,
-    /** Number of real UDataFileAccess values. @stable ICU 3.4 */
+#ifndef U_HIDE_DEPRECATED_API
+    /**
+     * Number of real UDataFileAccess values.
+     * @deprecated ICU 58 The numeric value may change over time, see ICU ticket #12420.
+     */
     UDATA_FILE_ACCESS_COUNT
+#endif  // U_HIDE_DEPRECATED_API
 } UDataFileAccess;
 
 /**