Use clang-format 3.8 to format VIXL

Additionally, this version of clang-format orders include directives
alphabetically which showed that the "non-const-visitor.h" header was missing
two of them.

Change-Id: Ib03407dd2046a0bb7175370685e09fb3aebe583f
diff --git a/test/test-runner.cc b/test/test-runner.cc
index 844c0b0..5d9ec9c 100644
--- a/test/test-runner.cc
+++ b/test/test-runner.cc
@@ -24,9 +24,9 @@
 // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+#include <cstdio>
 #include <cstdlib>
 #include <cstring>
-#include <cstdio>
 
 #include "test-runner.h"