include/maxscale/gw.h removed.

In a subsequent change, the includes of server/core/*.c will be
cleaned up, and if there is a common set of include files, needed
by most, then a server/core/maxscale/core.h that includes those
will be introduced.

server/modules/protocol/HTTPD/httpd.c

@@ -33,9 +33,9 @@
  */
 
 #include "httpd.h"
+#include <ctype.h>
 #include <maxscale/alloc.h>
 #include <maxscale/gw_protocol.h>
-#include <maxscale/gw.h>
 #include <maxscale/modinfo.h>
 #include <maxscale/log_manager.h>
 #include <maxscale/resultset.h>