Fix medium-ip not compiling complaining of needing EthernetAddress

.github/workflows/test.yml

@@ -41,6 +41,7 @@ jobs:
           - std medium-ethernet proto-ipv6 socket-tcp
           - std medium-ethernet medium-ip proto-ipv4 socket-icmp socket-tcp
           - std medium-ip proto-ipv6 socket-icmp socket-tcp
+          - std medium-ip proto-ipv4 proto-ipv6 socket-tcp socket-udp
 
           # Test features chosen to be as aggressive as possible.
           - std medium-ethernet medium-ip medium-ieee802154 proto-ipv4 proto-ipv6 socket-raw socket-udp socket-tcp socket-icmp socket-dns async

src/iface/interface/mod.rs

@@ -79,7 +79,7 @@ impl<'a> OutPackets<'a> {
 }
 
 #[allow(unused)]
-#[cfg(feature = "proto-ipv4")]
+#[cfg(feature = "proto-ipv4-fragmentation")]
 pub(crate) struct Ipv4OutPacket<'a> {
     /// The buffer that holds the unfragmented 6LoWPAN packet.
     buffer: ManagedSlice<'a, u8>,