Linux: Make sure sockaddr.sun_path is always '\0'-terminated
Linux: Make sure sockaddr.sun_path is always '\0'-terminated

Never fill the last byte of the buffer, so the string always stays
terminated.

While not all implementation strictly need that, the man page strongly
recommends it.

This shouldn't actually make a difference for our present use case, as
the (constant) string we are using is much shorter anyways. Still,
better to have it correct -- who knows where this code ends up down the
line...

servo/ipc-channel