Revert "Merge to upstream r304942."

This reverts commit 83b1388ecd, reversing
changes made to f20819f925.

Test: treehugger
Bug: None

src/functional.cpp

@@ -1,26 +0,0 @@
-//===----------------------- functional.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.
-//
-//===----------------------------------------------------------------------===//
-
-#include "functional"
-
-_LIBCPP_BEGIN_NAMESPACE_STD
-
-#ifdef _LIBCPP_ABI_BAD_FUNCTION_CALL_KEY_FUNCTION
-bad_function_call::~bad_function_call() _NOEXCEPT
-{
-}
-
-const char*
-bad_function_call::what() const _NOEXCEPT
-{
-    return "std::bad_function_call";
-}
-#endif
-
-_LIBCPP_END_NAMESPACE_STD