raw_ostream: Forward declare OpenFlags and include FileSystem.h only where necessary.

llvm-svn: 207593

llvm/lib/Target/TargetMachineC.cpp

@@ -18,6 +18,7 @@
 #include "llvm/IR/Module.h"
 #include "llvm/PassManager.h"
 #include "llvm/Support/CodeGen.h"
+#include "llvm/Support/FileSystem.h"
 #include "llvm/Support/FormattedStream.h"
 #include "llvm/Support/Host.h"
 #include "llvm/Support/TargetRegistry.h"