Update ICU to 58.1

source/i18n/unicode/fieldpos.h

Index: source/i18n/unicode/fieldpos.h
diff --git a/source/i18n/unicode/fieldpos.h b/source/i18n/unicode/fieldpos.h
index 38a9576e782a93ec642333bfbb9870da7794db91..ad75b77f8de64d6bf32e1aeeeb8c0b2f3d9b9578 100644
--- a/source/i18n/unicode/fieldpos.h
+++ b/source/i18n/unicode/fieldpos.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) 1997-2006, International Business Machines
@@ -56,7 +58,7 @@ U_NAMESPACE_BEGIN
  * to perform partial formatting or to get information about the
  * formatted output (such as the position of a field).
  *
- * The FieldPosition class is not suitable for subclassing.
+ * The FieldPosition class is not intended for public subclassing.
  *
  * <p>
  * Below is an example of using <code>FieldPosition</code> to aid
@@ -107,7 +109,8 @@ class U_I18N_API FieldPosition : public UObject {
 public:
     /**
      * DONT_CARE may be specified as the field to indicate that the
-     * caller doesn't need to specify a field.  Do not subclass.
+     * caller doesn't need to specify a field.
+     * @stable ICU 2.0
      */
     enum { DONT_CARE = -1 };