bug 232347: fix netmount to respect _netdev option
bug 232347: fix netmount to respect _netdev option

The _netdev option in fstab on linux systems indicates
that a filesystem should only be mounted if the network is available.

This commit fixes netmount to support this.

dwfreed/openrc,dwfreed/openrc,OpenRC/openrc,williamh/openrc,dwfreed/openrc,williamh/openrc,OpenRC/openrc,OpenRC/openrc,williamh/openrc