Update ICU to 58.1

source/common/unicode/stringpiece.h

Index: source/common/unicode/stringpiece.h
diff --git a/source/common/unicode/stringpiece.h b/source/common/unicode/stringpiece.h
index b29571d4adbbdd9d6d832aaeb0f9768b24161a56..5e40d4aca9b758eaa3c03e212339ab45b72bfd52 100644
--- a/source/common/unicode/stringpiece.h
+++ b/source/common/unicode/stringpiece.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) 2009-2013, International Business Machines
 // Corporation and others. All Rights Reserved.
 //
@@ -40,9 +42,9 @@ U_NAMESPACE_BEGIN
  * in a "const char*" or a "string" wherever a "StringPiece" is
  * expected.
  *
- * Functions or methods may use const StringPiece& parameters to accept either
- * a "const char*" or a "string" value that will be implicitly converted to
- * a StringPiece.
+ * Functions or methods may use StringPiece parameters to accept either a
+ * "const char*" or a "string" value that will be implicitly converted to a
+ * StringPiece.
  *
  * Systematic usage of StringPiece is encouraged as it will reduce unnecessary
  * conversions from "const char*" to "string" and back again.