Mark test as a long-test

[rogfer01]

Summary

This test creates a string of 2GiB which may make it too slow to run in a simulator.

[rogfer01]

Friendly ping :)

[olista01]

LGTM.

libcxx/trunk/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.put.area/pbump2gig.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 // <streambuf>
 
 // template <class charT, class traits = char_traits<charT> >
 // class basic_streambuf;
 
 // void pbump(int n);
+//
+// REQUIRES: long_tests
 
 #include <sstream>
 #include <cassert>
 #include "test_macros.h"
 
 struct SB : std::stringbuf
 {
   SB() : std::stringbuf(std::ios::ate|std::ios::out) { }