busybox: Improve syslog restart handling

We're seeing races on the autobuilder where syslogd fails to shut down
fast enough to be restarted leading to failures.

Add some checks to ensure when restarting that processes exit before
being restarted.

(From OE-Core rev: 04de384256ad321834cf5e3dbb9a8d3ea2ab66c2)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/busybox/files/syslog

@@ -51,6 +51,22 @@ else
 	SYSLOG_ARGS="-C"
 fi
 
+waitpid ()
+{
+  pid=$1
+  # Give pid a chance to exit before we restart with a 5s timeout in 1s intervals
+  if [ -z "$pid" ]; then
+    return
+  fi
+  timeout=5;
+  while [ $timeout -gt 0 ]
+  do
+    timeout=$(( $timeout-1 ))
+    kill -0 $pid 2> /dev/null || break
+    sleep 1
+  done
+}
+
 case "$1" in
   start)
 	echo -n "Starting syslogd/klogd: "
@@ -65,7 +81,11 @@ case "$1" in
 	echo "done"
 	;;
   restart)
-  	$0 stop
+	pid1=`pidof syslogd`
+	pid2=`pidof syslogd`
+	$0 stop
+	waitpid $pid1
+	waitpid $pid2
 	$0 start
 	;;
   *)