Fix and test format %C

test/date_test/format/range.pass.cpp

@@ -1,6 +1,6 @@
 // The MIT License (MIT)
 //
-// Copyright (c) 2015, 2016 Howard Hinnant
+// Copyright (c) 2016 Howard Hinnant
 //
 // Permission is hereby granted, free of charge, to any person obtaining a copy
 // of this software and associated documentation files (the "Software"), to deal
@@ -34,8 +34,6 @@ using microfortnights = std::chrono::duration<std::int64_t,
                                               std::ratio_multiply<fortnights::period,
                                                                   std::micro>>;
 
-#include <iostream>
-
 int
 main()
 {
@@ -69,6 +67,4 @@ main()
     os.str("");
     os << format("%F %T", sys_days{dec/last/year::max()} + microfortnights{1});
     assert(os.str() == "32767-12-31 00:00:01.2096");
-    os.str("");
-    os.str("");
 }