missing.h: add IFLA_MACVLAN_FLAGS

Now we are getting into kernel < 3.4 territory...

https://bugs.freedesktop.org/show_bug.cgi?id=80095

configure.ac

@@ -310,7 +310,8 @@ AC_CHECK_DECLS([gettid, pivot_root, name_to_handle_at, setns, LO_FLAGS_PARTSCAN]
 #include <linux/loop.h>
 ]])
 
-AC_CHECK_DECLS([IFLA_PHYS_PORT_ID,
+AC_CHECK_DECLS([IFLA_MACVLAN_FLAGS,
+                IFLA_PHYS_PORT_ID,
                 IFLA_BOND_AD_INFO,
                 IFLA_VLAN_PROTOCOL,
                 IFLA_VXLAN_LOCAL6,

src/shared/missing.h

@@ -371,6 +371,15 @@ static inline int setns(int fd, int nstype) {
 #define LOOP_CTL_GET_FREE 0x4C82
 #endif
 
+#if !HAVE_DECL_IFLA_MACVLAN_FLAGS
+#define IFLA_MACVLAN_UNSPEC 0
+#define IFLA_MACVLAN_MODE 1
+#define IFLA_MACVLAN_FLAGS 2
+#define __IFLA_MACVLAN_MAX 3
+
+#define IFLA_MACVLAN_MAX (__IFLA_MACVLAN_MAX - 1)
+#endif
+
 #if !HAVE_DECL_IFLA_PHYS_PORT_ID
 #undef IFLA_PROMISCUITY
 #define IFLA_PROMISCUITY 30