chardev/char-socket: tcp_chr_recv: don't clobber errno

chardev/char-socket: tcp_chr_recv: don't clobber errno

tcp_chr_recv communicates the specific error condition to the caller via
errno.  However, after setting it, it may call into some system calls or
library functions which can clobber the errno.

Avoid this by moving the errno assignment to the end of the function.

Signed-off-by: Roman Kagan <rvkagan@yandex-team.ru>
Message-Id: <20211111153354.18807-3-rvkagan@yandex-team.ru>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>