Add .clang-format and run clang-format on runtime/platform.

runtime/platform/floating_point_win.cc

Index: runtime/platform/floating_point_win.cc
diff --git a/runtime/platform/floating_point_win.cc b/runtime/platform/floating_point_win.cc
index 76ce626507a6396a10b8937145857fdd60cf0deb..8863ec5f8f090630f2eb463b8b31839f3d58a6d9 100644
--- a/runtime/platform/floating_point_win.cc
+++ b/runtime/platform/floating_point_win.cc
@@ -38,9 +38,8 @@ double atan2_ieee(double x, double y) {
     // Same is with index_y.
     int index_x = (cls_x & _FPCLASS_PINF) != 0 ? 0 : 1;
     int index_y = (cls_y & _FPCLASS_PINF) != 0 ? 0 : 1;
-    static double atans_at_infinities[2][2] =
-      { { atan2(1.,  1.), atan2(1.,  -1.) },
-        { atan2(-1., 1.), atan2(-1., -1.) } };
+    static double atans_at_infinities[2][2] = {
+        {atan2(1., 1.), atan2(1., -1.)}, {atan2(-1., 1.), atan2(-1., -1.)}};
     return atans_at_infinities[index_x][index_y];
   } else {
     return atan2(x, y);