Cleanup _LIBCPP_HAS_NO_<c++11-feature> in the input.output library

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@300626 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/input.output/string.streams/stringstream.cons/move2.pass.cpp

@@ -7,6 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// UNSUPPORTED: c++98, c++03
+
 // <sstream>
 
 // template <class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
@@ -22,7 +24,6 @@
 
 int main()
 {
-#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
     std::vector<std::istringstream> vecis;
     vecis.push_back(std::istringstream());
     vecis.back().str("hub started at [00 6b 8b 45 69]");
@@ -34,5 +35,4 @@ int main()
         vecis[n].seekg(0, std::ios_base::beg);
         assert(vecis[n].str().size() == 31);
     }
-#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
 }