CMake: correct non-POSIX friendly 'sed-i' arg in FindPySide2Tools.cmake

[luzpaz]

resolves #4588
ticket: https://tracker.freecadweb.org/view.php?id=4588

[luzpaz]

@chennes got a moment to review?

[chennes]

The change looks fine, and in principle the two sed commands are the same -- I can't test it in a real application because I don't know where this macro is called from.

I personally didn't know that the -i option was non-POSIX, so you might consider tweaking the comment above this where it says "in-place" to specifically note that you aren't using -i for that reason.

[luzpaz]

Thanks @chennes I tweaked the comment per your advice. Good catch. I added a [skip ci] the commit message to avoid an unnecessary compile due to a comment change.

@wwmayer this should be ready for merge.

[luzpaz]

Note: this PR was a patch that was submitted from the FreeBSD folks to make their already complex packaging tasks easier 😉

[wwmayer]

Here some background information:
The sed command has been introduced with 2b9da83#diff-70c718cc8ed63da585359f36123ba88fb61574e5d4531161d76d954f94434f2b where the openSuse maintainers wanted to avoid changing checksums because of the build date of the generated file.

With a later change the execute_command function was replaced with a add_custom_command that uses the -i option: 75c698d#diff-70c718cc8ed63da585359f36123ba88fb61574e5d4531161d76d954f94434f2b