Add missing <memory> include in test

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@283633 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/utilities/tuple/tuple.tuple/tuple.assign/copy.pass.cpp

@@ -16,6 +16,7 @@
 // UNSUPPORTED: c++98, c++03
 
 #include <tuple>
+#include <memory>
 #include <string>
 #include <cassert>