Add ipc-notify program for custom scripting

[krakowski]

This PR adds a slightly modified version of ipc_read enabling functionality similar to hooks. The program accepts an additional --command parameter which is expected to be a path to a script/program. Once a message arrives the specified program is called with the message as the first parameter.

Autostarting this program on boot enables the user to execute custom scripts/programs on any event.

Example

ipc_notify -n 2 -c "/bin/ash /tmp/sd/yi-hack/script/echo_event.sh"

echo_event.sh

#!/bin/ash

echo "${1}"

[roleoroleo]

Thank you for your PR.
Can I add this feature to the other repos?
MStar and Allwinner?

[krakowski]

Sorry, I was on vacation. Sure, feel free to use it in the other repos as well 🙂