Minor libc++abi changes to make things build better with gcc.


git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@211748 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/src/cxa_default_handlers.cpp b/src/cxa_default_handlers.cpp
index 27ffb71..a26ea2a 100644
--- a/src/cxa_default_handlers.cpp
+++ b/src/cxa_default_handlers.cpp
@@ -13,6 +13,7 @@
 #include <new>
 #include <exception>
 #include "abort_message.h"
+#include "config.h" // For __sync_swap
 #include "cxxabi.h"
 #include "cxa_handlers.hpp"
 #include "cxa_exception.hpp"