SSH connection status indicators

- Add Connected bool field to vfs.Entry and RemoteMount
- Track connection status in sshState.connectedHosts
- Show status icon (connected/disconnected) in pane header when browsing remote host
- Async SSH connection test with cancel support for Add Host dialog
- Colored labels and styled help text in SSH dialogs
- Confirmation dialog when deleting manually-added SSH hosts

vendor/golang.org/x/sys/unix/syscall_unix.go

@@ -367,7 +367,9 @@ func Recvmsg(fd int, p, oob []byte, flags int) (n, oobn int, recvflags int, from
 		iov[0].SetLen(len(p))
 	}
 	var rsa RawSockaddrAny
-	n, oobn, recvflags, err = recvmsgRaw(fd, iov[:], oob, flags, &rsa)
+	if n, oobn, recvflags, err = recvmsgRaw(fd, iov[:], oob, flags, &rsa); err != nil {
+		return
+	}
 	// source address is only specified if the socket is unconnected
 	if rsa.Addr.Family != AF_UNSPEC {
 		from, err = anyToSockaddr(fd, &rsa)
@@ -389,8 +391,10 @@ func RecvmsgBuffers(fd int, buffers [][]byte, oob []byte, flags int) (n, oobn in
 		}
 	}
 	var rsa RawSockaddrAny
-	n, oobn, recvflags, err = recvmsgRaw(fd, iov, oob, flags, &rsa)
-	if err == nil && rsa.Addr.Family != AF_UNSPEC {
+	if n, oobn, recvflags, err = recvmsgRaw(fd, iov, oob, flags, &rsa); err != nil {
+		return
+	}
+	if rsa.Addr.Family != AF_UNSPEC {
 		from, err = anyToSockaddr(fd, &rsa)
 	}
 	return