libcxx: Disable CFI in function std::get_temporary_buffer.

The specification of this function mandates a cast to uninitialized
T*, which is forbidden under CFI.

Differential Revision: https://reviews.llvm.org/D42146

llvm-svn: 322744
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: b89956c812bbb4d3196acb2e0db49051ad3d6e20
diff --git a/include/memory b/include/memory
index 56502e2..2273731 100644
--- a/include/memory
+++ b/include/memory
@@ -1992,6 +1992,7 @@
 };
 
 template <class _Tp>
+_LIBCPP_NO_CFI
 pair<_Tp*, ptrdiff_t>
 get_temporary_buffer(ptrdiff_t __n) _NOEXCEPT
 {