Sort the #include lines for unittests/...

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

llvm-svn: 169243
diff --git a/clang/unittests/Basic/FileManagerTest.cpp b/clang/unittests/Basic/FileManagerTest.cpp
index 91998b6..0a83a3a 100644
--- a/clang/unittests/Basic/FileManagerTest.cpp
+++ b/clang/unittests/Basic/FileManagerTest.cpp
@@ -7,10 +7,9 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "clang/Basic/FileManager.h"
 #include "clang/Basic/FileSystemOptions.h"
 #include "clang/Basic/FileSystemStatCache.h"
-#include "clang/Basic/FileManager.h"
-
 #include "gtest/gtest.h"
 
 using namespace llvm;