Update LLVM for 3.5 rebase (r209712).

Change-Id: I149556c940fb7dc92d075273c87ff584f400941f
diff --git a/lib/Bitcode/Writer/BitWriter.cpp b/lib/Bitcode/Writer/BitWriter.cpp
index 0275f96..3747122 100644
--- a/lib/Bitcode/Writer/BitWriter.cpp
+++ b/lib/Bitcode/Writer/BitWriter.cpp
@@ -10,6 +10,7 @@
 #include "llvm-c/BitWriter.h"
 #include "llvm/Bitcode/ReaderWriter.h"
 #include "llvm/IR/Module.h"
+#include "llvm/Support/FileSystem.h"
 #include "llvm/Support/raw_ostream.h"
 using namespace llvm;