Prep v220: Remove all source files, taht are not needed to build elogind.
Prep v220: Remove not needed headers, round 1
Prep v220: Remove not needed headers, round 2
Prep v220: Remove not needed headers, round 3
Prep v220: Remove empty source directories
Prep v220: Remove non-empty source directories, that aren't needed by elogind
Prep v220: Remove all root directories that aren't referenced by the elogind build chain.
Prep v220: remove superfluous src/import directory and systemd configurations and policies.