Put std::piecewise_construct_t back into the dylib for ABI stability.  When clients are in C++11/constexpr mode this will be safely ignored because piecewise_construct is then declared with internal linkage.

llvm-svn: 153981
diff --git a/libcxx/src/utility.cpp b/libcxx/src/utility.cpp
index deb5ffa..e9830e7 100644
--- a/libcxx/src/utility.cpp
+++ b/libcxx/src/utility.cpp
@@ -7,12 +7,11 @@
 //
 //===----------------------------------------------------------------------===//
 
+#define _LIBCPP_BUILDING_UTILITY
 #include "utility"
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#ifdef _LIBCPP_HAS_NO_CONSTEXPR
 const piecewise_construct_t piecewise_construct = {};
-#endif
 
 _LIBCPP_END_NAMESPACE_STD