Introduce a lock file in non-persistent storage /run/network/ifstatelock

to make sure the state file in persistent storage is cleaned up
correctly

Ticket: CM-7774
Reviewed By: CCR-3623
Testing Done: Tested statefile accross reboots

ifupdown2 state file was moved to /var/tmp because /var/tmp was tmpfs
and was large enough (100MB) for the state file. But it appears it has
changed (or is not consistent) across all platforms. We can move it
under /run, but /run again size varies on various platforms and it is
too small on some platforms.

This patch:
- continues to keep the ifupdown2 state file under /var/tmp (because it
needs the space)
- ntroduces a second level /run/network/ifstatelock file that stays on
non-persistant storage and is used to delete the state file at /boot up

init.d/networking

@@ -11,7 +11,10 @@
 
 PATH="/sbin:/bin"
 RUN_DIR="/run/network"
-IFSTATE="$RUN_DIR/ifstate"
+IFSTATE_LOCKFILE="${RUN_DIR}/ifstatelock"
+
+STATE_DIR="/var/tmp/network"
+IFSTATE_FILE="${STATE_DIR}/ifstatenew"
 
 NAME=networking
 SCRIPTNAME=/etc/init.d/$NAME
@@ -37,7 +40,7 @@ gen_examples() {
     #
 
     # generate files only at boot
-    [ -f /var/tmp/network/ifstatenew ] && return
+    [ -f ${IFSTATE_LOCKFILE} ] && return
 
     python_ifupdown2_docdir="/usr/share/doc/python-ifupdown2"
     swpfile=${python_ifupdown2_docdir}"/examples/swp_defaults"
@@ -52,7 +55,7 @@ gen_examples() {
 
 perf_options() {
     # At bootup lets set perfmode
-    [ -f /var/tmp/network/ifstatenew ] && echo -n "" && return
+    [ -f ${IFSTATE_LOCKFILE} ] && echo -n "" && return
 
     echo -n "--perfmode"
 }
@@ -124,6 +127,8 @@ ifup_hotplug () {
 }
 
 ifupdown_init() {
+    	# remove state file at boot
+	[ ! -e ${IFSTATE_LOCKFILE} ] && rm -f ${IFSTATE_FILE}
 	[ ! -e /run/network ] && mkdir -p /run/network &>/dev/null
 	[ ! -e /etc/network/run ] && \
 		ln -sf /run/network /etc/network/run &>/dev/null