Sort the #include lines for unittests/...

I've tried to place sensible headers at the top as main-module headers.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@169243 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/unittests/Tooling/TestVisitor.h b/unittests/Tooling/TestVisitor.h
index 8333c24..ce3246a 100644
--- a/unittests/Tooling/TestVisitor.h
+++ b/unittests/Tooling/TestVisitor.h
@@ -15,15 +15,14 @@
 #ifndef LLVM_CLANG_TEST_VISITOR_H
 #define LLVM_CLANG_TEST_VISITOR_H
 
-#include <vector>
-
-#include "clang/AST/ASTContext.h"
 #include "clang/AST/ASTConsumer.h"
+#include "clang/AST/ASTContext.h"
 #include "clang/AST/RecursiveASTVisitor.h"
-#include "clang/Frontend/FrontendAction.h"
 #include "clang/Frontend/CompilerInstance.h"
+#include "clang/Frontend/FrontendAction.h"
 #include "clang/Tooling/Tooling.h"
 #include "gtest/gtest.h"
+#include <vector>
 
 namespace clang {