Move headers from server/include to include/maxscale

- Headers now to be included as <maxscale/xyz.h>
- First step, no cleanup of headers has been made. Only moving
  from one place to another + necessary modifications.

query_classifier/qc_sqlite/builtin_functions.c

@@ -5,7 +5,7 @@
 #include "builtin_functions.h"
 #include <stdlib.h>
 #include <string.h>
-#include <skygw_debug.h>
+#include <maxscale/skygw_debug.h>
 
 static struct
 {