Rather than make this a Linux test, we should just test for the existence

of endian.h.  I figure that if it exists it's pretty sure that it has
the byte order information and we may catch some other ports without
any further testing.

From: "D'Arcy J.M. Cain" <darcy@druid.net>

src/backend/libpq/pqcomprim.c

@@ -1,6 +1,10 @@
 #include <stdlib.h>
 #include <stdio.h>
 
+#ifdef        HAVE_ENDIAN_H
+#  include    <endian.h>
+#endif
+
 #include "postgres.h"
 #include "libpq/pqcomm.h"