Check for <linux/dccp.h> before including it

configure.ac

@@ -796,7 +796,7 @@ AC_CHECK_HEADERS(sys/sockio.h fcntl.h sys/types.h sys/time.h sys/times.h sys/ioc
 AC_CHECK_HEADERS([arpa/inet.h net/if.h netinet/in.h sys/socket.h netinet/udplite.h])
 if test "${SYS}" != "mingw32" -a "${SYS}" != "mingwce"; then
 AC_CHECK_HEADERS(machine/param.h sys/shm.h)
-AC_CHECK_HEADERS(linux/version.h)
+AC_CHECK_HEADERS([linux/version.h linux/dccp.h])
 AC_CHECK_HEADERS(syslog.h)
 fi # end "${SYS}" != "mingw32" -a "${SYS}" != "mingwce"
 

src/network/udp.c

@@ -75,7 +75,7 @@
 # define IPPROTO_UDPLITE 136 /* IANA */
 #endif
 
-#ifdef __linux__
+#ifdef HAVE_LINUX_DCCP_H
 # include <linux/dccp.h>
 # ifndef SOCK_DCCP /* provisional API */
 #  define SOCK_DCCP 6