restart dnsmasq failed on LEDE 17.01.4 due to the pid file name changes.

[shawnchain]

network-feeds/minivtun-tools/files/usr/lib/minivtun/invoke.sh

Line 297 in daf8aff

local dnsmasq_pid=`cat /var/run/dnsmasq.pid 2>/dev/null || cat /var/run/dnsmasq/dnsmasq.pid 2>/dev/null`

changed to:
local dnsmasq_pid=`cat /var/run/dnsmasq.pid 2>/dev/null || cat /var/run/dnsmasq/dnsmasq.pid 2>/dev/null || pidof dnsmasq`