Sort the #include lines for tools/...

Again, tools are trickier to pick the main module header for than
library source files. I've started to follow the pattern of using
LLVMContext.h when it is included as a stub for program source files.

llvm-svn: 169252
diff --git a/llvm/tools/bugpoint/BugDriver.h b/llvm/tools/bugpoint/BugDriver.h
index cc78489..2b621ecc1 100644
--- a/llvm/tools/bugpoint/BugDriver.h
+++ b/llvm/tools/bugpoint/BugDriver.h
@@ -18,8 +18,8 @@
 
 #include "llvm/ADT/ValueMap.h"
 #include "llvm/Transforms/Utils/ValueMapper.h"
-#include <vector>
 #include <string>
+#include <vector>
 
 namespace llvm {