nbd: Update to 3.19 and remove unneed patches

nbd: Update to 3.19 and remove unneed patches

Current version in OpenWrt (3.16.2) fails against the Arch Linux
in System Rescue CD's NBD as rootfs (to allow sharing ISO across
network).  Based on resolved issues and web searching it seems
nbd had endianness issues (which affected my ath79 device).

This updates to 3.19 which allows System Rescue CD PXE boot with
NBD rootfs to work.

Removed patches no longer required due to upstream changes, and
added new configure option (--without-libnl) required to avoid
linking against full libnl and libnl-genl (if present in build).

Signed-off-by: Daniel F. Dickinson <cshored@thecshore.com>