Add a FIXME to a failing test.

(See discussion in the bug for why this isn't XFAILed.)



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@197991 91177308-0d34-0410-b5e6-96231b3b80d8

test/Headers/cxx11.cpp

 // RUN: %clang_cc1 -ffreestanding -fsyntax-only -std=c++11 %s
 // RUN: %clang_cc1 -ffreestanding -fsyntax-only -std=c++11 -fmodules %s
 
+// FIXME: This test fails on OS X 10.9 with headers in /usr/include, see PR18322
+
 #include <stdalign.h>
 
 #if defined alignas