latch: tweak the copyright and style

src/latch.cc

 /*
+ * Copyright 2010-2015, Tarantool AUTHORS, please see AUTHORS file.
+ *
  * Redistribution and use in source and binary forms, with or
  * without modification, are permitted provided that the following
  * conditions are met:
@@ -26,7 +28,6 @@
  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
-
 #include "latch.h"
 
 struct box_latch

src/latch.h

@@ -30,7 +30,6 @@
  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
-
 #include <assert.h>
 #include "salad/rlist.h"
 #include "fiber.h"