Update ICU to 58.1

source/common/messagepattern.cpp

Index: source/common/messagepattern.cpp
diff --git a/source/common/messagepattern.cpp b/source/common/messagepattern.cpp
index de0410b83c136a7cc10604c1f0128b1882195b20..31d5bb7b9a687edeaa5c5db5791064928559a1e9 100644
--- a/source/common/messagepattern.cpp
+++ b/source/common/messagepattern.cpp
@@ -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) 2011-2012, International Business Machines
@@ -114,7 +116,7 @@ MessagePatternList<T, stackCapacity>::copyFrom(
             errorCode=U_MEMORY_ALLOCATION_ERROR;
             return;
         }
-        uprv_memcpy(a.getAlias(), other.a.getAlias(), length*sizeof(T));
+        uprv_memcpy(a.getAlias(), other.a.getAlias(), (size_t)length*sizeof(T));
     }
 }