[master] Fix compilation issue on RHEL6.

Added missing fctnl.h include. Okayed on jabber.

src/lib/dhcp/tests/pkt_filter6_test_stub.cc

@@ -15,6 +15,7 @@
 #include <config.h>
 #include <exceptions/exceptions.h>
 #include <dhcp/tests/pkt_filter6_test_stub.h>
+#include <fcntl.h>
 #include <netinet/in.h>
 #include <list>
 

src/lib/dhcpsrv/dhcp4o6_ipc.cc

@@ -23,6 +23,7 @@
 #include <dhcpsrv/dhcp4o6_ipc.h>
 #include <boost/pointer_cast.hpp>
 #include <errno.h>
+#include <fcntl.h>
 #include <netinet/in.h>
 #include <string>