Revise include order using clang-format-6.0

Run the `clang-format.bash` script to update our C and C++ code to a new
include order `.clang-format`.  Use `clang-format` version 6.0.

Tests/FindPython/NumPy/arraytest.c

@@ -1,10 +1,10 @@
 #include "Python.h"
 
 #define NPY_NO_DEPRECATED_API NPY_1_7_API_VERSION
-#include "numpy/arrayobject.h"
-
 #include <math.h>
 
+#include "numpy/arrayobject.h"
+
 static PyObject* vecsq(PyObject* self, PyObject* args);
 
 static PyMethodDef arraytestMethods[] = { { "vecsq", vecsq, METH_VARARGS },