ipnetns: fix build on older systems
Debian Squeeze has out of date <sys/mount.h> without the required flags.
diff --git a/ip/ipnetns.c b/ip/ipnetns.c
index b047b97..c9bc20a 100644
--- a/ip/ipnetns.c
+++ b/ip/ipnetns.c
@@ -29,6 +29,20 @@
#define MNT_DETACH 0x00000002 /* Just detach from the tree */
#endif /* MNT_DETACH */
+/* sys/mount.h may be out too old to have these */
+#ifndef MS_REC
+#define MS_REC 16384
+#endif
+
+#ifndef MS_SLAVE
+#define MS_SLAVE (1 << 19)
+#endif
+
+#ifndef MS_SHARED
+#define MS_SHARED (1 << 20)
+#endif
+
+
#ifndef HAVE_SETNS
static int setns(int fd, int nstype)
{
