Find the correct install paths for systemd units and udev rules

[PVermeer]

Description

• Added FindSystemd.cmake
• Added FindUdev.cmake
• Edited linux.cmake to load these two new modules and read the new path variables for these modules

Instead of using CMAKE_INSTALL_LIBDIR to get the system lib directory where a library would be installed (can be 'lib' or 'lib64'), now the actual install path of systemd and udev are queried via pkg-config. This should be more reliable for linux builds.

My knowledge of cmake is limited so a review would appreciated.

Issues Fixed or Closed

• Fixes [Nightly] Systemd sunshine service not found in nightly and perhaps udev rules are not installed. #2038

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Dependency update (updates to dependencies)
• Documentation update (changes to documentation)
• Repository update (changes to repository files, e.g. .github/...)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated the in code docstring/documentation-blocks for new or existing methods/components

Branch Updates

LizardByte requires that branches be up-to-date before merging. This means that after any PR is merged, this branch
must be updated before it can be merged. You must also
Allow edits from maintainers.

• I want maintainers to keep my branch updated

[CLAassistant]

All committers have signed the CLA.

[ReenigneArcher]

I'm assuming these FindX files are not re-used from anywhere.

I tried searching, but the closest I found was

• https://invent.kde.org/frameworks/extra-cmake-modules/-/blob/master/find-modules/FindUDev.cmake
• https://github.com/wireshark/wireshark/blob/master/cmake/modules/FindSystemd.cmake

[ReenigneArcher]

Looks like some linting errors to fix, and it fails on debian distros. Does something else need to be installed there?

[PVermeer]

I'm assuming these FindX files are not re-used from anywhere.

I tried searching, but the closest I found was

* https://invent.kde.org/frameworks/extra-cmake-modules/-/blob/master/find-modules/FindUDev.cmake

* https://github.com/wireshark/wireshark/blob/master/cmake/modules/FindSystemd.cmake

I was inspired by:

• https://github.com/ximion/limba/blob/master/data/cmake/systemdservice.cmake

And further the cmake docs

[PVermeer]

Looks like some linting errors to fix, and it fails on debian distros. Does something else need to be installed there?

Should work. I only tested the fedora 39 container locally. I will check debian based containers later and also replace tabs with spaces for the linter. My vscode went wild with all the different formatting in the cmake files ;).

[PVermeer]

Looks like some linting errors to fix, and it fails on debian distros. Does something else need to be installed there?

Linting should be fixed now and indeed udev was not installed by default on the Debian images. This is now fixed.

Also the variable for querying the systemd unit install dirs did not work on Ubuntu 20.x. Now using an older alias that works on all distros.

Tested all docker files locally so I think everything should work now :).