BUILD: include: add sys/types before netinet/tcp.h

Apparently Cygwin requires sys/types.h before netinet/tcp.h but doesn't
include it by itself, as shown here:
  https://github.com/haproxy/haproxy/actions/runs/131943890

This patch makes sure it's always present, which is in server.c and
the SPOA example.

contrib/spoa_example/spoa.c

@@ -22,6 +22,7 @@
 #include <stdio.h>
 #include <signal.h>
 #include <arpa/inet.h>
+#include <sys/types.h>
 #include <netinet/in.h>
 #include <netinet/tcp.h>
 #include <sys/socket.h>

src/server.c

@@ -11,6 +11,7 @@
  *
  */
 
+#include <sys/types.h>
 #include <netinet/tcp.h>
 #include <ctype.h>
 #include <errno.h>