ART: Include cleanup

Let clang-format reorder the header includes.

Derived with:

* .clang-format:
 BasedOnStyle: Google
 IncludeIsMainRegex: '(_test|-inl)?$'

* Steps:
 find . -name '*.cc' -o -name '*.h' | xargs sed -i.bak -e 's/^#include/ #include/' ; git commit -a -m 'ART: Include cleanup'
 git-clang-format -style=file HEAD^
 manual inspection
 git commit -a --amend

Test: mmma art
Change-Id: Ia963a8ce3ce5f96b5e78acd587e26908c7a70d02
diff --git a/compiler/optimizing/nodes_test.cc b/compiler/optimizing/nodes_test.cc
index 7686ba8..f3a78a0 100644
--- a/compiler/optimizing/nodes_test.cc
+++ b/compiler/optimizing/nodes_test.cc
@@ -14,8 +14,9 @@
  * limitations under the License.
  */
 
-#include "base/arena_allocator.h"
 #include "nodes.h"
+
+#include "base/arena_allocator.h"
 #include "optimizing_unit_test.h"
 
 #include "gtest/gtest.h"