Move #pragma to first line in each header

The `#pragma once` is now on the first line of each header.

server/modules/routing/schemarouter/schemarouter.hh

@@ -1,3 +1,4 @@
+#pragma once
 /*
  * Copyright (c) 2016 MariaDB Corporation Ab
  *
@@ -11,8 +12,6 @@
  * Public License.
  */
 
-#pragma once
-
 /**
  * @file schemarouter.hh - Common schemarouter definitions
  */