New comment by Duncaen on void-packages repository

https://github.com/void-linux/void-packages/pull/20098#issuecomment-601189877

Comment:
I'm not completely happy with it, I would like to have a mechanism to completely disable sigpwr for non containers and users who may run a UPS that sends sigpwr but don't want this to shutdown the system or handle in some other way.

This also requires man page updates, we shouldn't just change how init behaves when it is signaled without documenting it and considering edge cases.

I would add `/etc/runit/sigpwr` which is checked for for existence and executable bit.
Create it from our core services, and `chmod u+x` it if it is a "container" system.

This would not change anything for normal users, introduce the wanted behavior for "containers" and allows users with USPs that send a signal to pid 1 to enable it by `chmod u+x` the file.