Add back improperly removed #include for config.h.

This probably ought to be kept in *all* the port files, but these two
are the only ones that generated compiler warnings for me ...

src/backend/port/random.c

-/* $Id: random.c,v 1.8 1999/07/16 03:13:06 momjian Exp $ */
+/* $Id: random.c,v 1.9 1999/07/16 23:09:45 tgl Exp $ */
 
 #include <stdlib.h>
 #include <math.h>
 #include <errno.h>
 
+#include "config.h"
+
 long
 random()
 {

src/backend/port/srandom.c

-/* $Id: srandom.c,v 1.8 1999/07/16 03:13:08 momjian Exp $ */
+/* $Id: srandom.c,v 1.9 1999/07/16 23:09:45 tgl Exp $ */
 
 #include <stdlib.h>
 #include <math.h>
 #include <errno.h>
 
+#include "config.h"
+
 void
 srandom(unsigned int seed)
 {