I don't kown much about what a socketpair implementation is, but it seems that it's not available in the arm kernel.

Empeg kernels are build without "System V IPC" to keep the size down. I expect this is what's causing the lack of socketpair(). You could try recompiling sshd, persuading it to use pipe() instead (which is supported); otherwise, you need to rebuild and reflash the kernel. You'll also need System V IPC if you want to use Samba.

Peter