Follow LLVM header file shuffling

This allows us to compile against revision 138708. I need this, because
the version we currently use is causing mysterious corruption of object
files during linking on win, apparently triggered by my vec-representation
patch.

Author: marijnh

src/rustllvm/RustWrapper.cpp

@@ -19,8 +19,8 @@
 #include "llvm/Support/Timer.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetMachine.h"
-#include "llvm/Target/TargetSelect.h"
-#include "llvm/Target/TargetRegistry.h"
+#include "llvm/Support/TargetSelect.h"
+#include "llvm/Support/TargetRegistry.h"
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Support/Host.h"
 #include "llvm-c/Core.h"