Cleanup: locate break statements inside the case body

Follow the convention used almost everywhere in Blender's code.

source/blender/freestyle/intern/python/BPy_StrokeAttribute.cpp

@@ -516,12 +516,14 @@ static int StrokeAttribute_mathutils_set_index(BaseMathObject *bmo, int subtype,
       float g = (index == 1) ? bmo->data[1] : self->sa->getColorG();
       float b = (index == 2) ? bmo->data[2] : self->sa->getColorB();
       self->sa->setColor(r, g, b);
-    } break;
+      break;
+    }
     case MATHUTILS_SUBTYPE_THICKNESS: {
       float tr = (index == 0) ? bmo->data[0] : self->sa->getThicknessR();
       float tl = (index == 1) ? bmo->data[1] : self->sa->getThicknessL();
       self->sa->setThickness(tr, tl);
-    } break;
+      break;
+    }
     default:
       return -1;
   }