fix wait_queue rmmod deadlock, wait_queue2, add insrm.sh that was used to test wait_queue lock, which obsoletes workqueue_cheat.sh

rootfs_overlay/insrm.sh

@@ -0,0 +1,13 @@
+#!/bin/sh
+# Insert and remove a module n times to check for spurious errors / deadlocks.
+set -e
+mod="$1"
+n="${2:-1}"
+i=0
+while [ $i -lt $n ]; do
+  echo "insmod $i"
+  insmod "/$mod.ko"
+  echo "rmmod $i"
+  rmmod "$mod"
+  i=$(($i+1))
+done