Update ICU to 58.1

source/i18n/decimfmtimpl.h

Index: source/i18n/decimfmtimpl.h
diff --git a/source/i18n/decimfmtimpl.h b/source/i18n/decimfmtimpl.h
index 9193d57e8f5169ba7e2559f3003e190864dd6ee3..82f154edbd3557335ad9458a66beb0d716431ed5 100644
--- a/source/i18n/decimfmtimpl.h
+++ b/source/i18n/decimfmtimpl.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) 2015, International Business Machines
@@ -217,7 +219,7 @@ UnicodeString &format(
         FieldPositionIterator *posIter,
         UErrorCode &status) const;
 UnicodeString &format(
-        const StringPiece &number,
+        StringPiece number,
         UnicodeString &appendTo,
         FieldPositionIterator *posIter,
         UErrorCode &status) const;