Prepare for running on top of new libc++abi.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@149634 91177308-0d34-0410-b5e6-96231b3b80d8

src/typeinfo.cpp

@@ -13,6 +13,8 @@
 
 #include "typeinfo"
 
+#ifndef _LIBCPPABI_VERSION
+
 std::bad_cast::bad_cast() _NOEXCEPT
 {
 }
@@ -48,3 +50,4 @@ std::bad_typeid::what() const _NOEXCEPT
   void __cxxabiv1::__cxa_bad_cast() { throw std::bad_cast(); }
 #endif
 
+#endif  // _LIBCPPABI_VERSION