[IS_AUTOIF] Add support for /etc/network/interface.d

CHANGELOG

@@ -4,6 +4,7 @@ and this project **does not adhere to [Semantic Versioning](http://semver.org/sp
 ## [Unreleased]
 
 ### Added
+* IS_AUTOIF: add support for /etc/network/interfaces.d
 
 ### Changed
 

evocheck.sh

@@ -582,7 +582,7 @@ check_autoif() {
         interfaces=$(/sbin/ifconfig -s | tail -n +2 | grep -E -v "^(lo|vnet|docker|veth|tun|tap|macvtap|vrrp)" | cut -d " " -f 1 |tr "\n" " ")
     fi
     for interface in $interfaces; do
-        if ! grep -q "^auto $interface" /etc/network/interfaces; then
+        if ! grep -Rq "^auto $interface" /etc/network/interfaces*; then
             failed "IS_AUTOIF" "Network interface \`${interface}' is not set to auto"
             test "${VERBOSE}" = 1 || break
         fi