* chore(organization): allow nested header and c files
* feat: add shell login "middleware" & etc:
* lidm now calls `bash` (or other shells, depends on PACKAGE cfg) in
login mode as a session wrapper to source most env (can be disabled)
* this fixes a lot of env problems with all `/etc/profile` and more
Extra:
* implemented a musl compatible version of `execvpe` and now lidm should
search for PATH everywhere it needs to
* `search_path` now also checks if the found binary is properly
executable
* lidm now uses `confstr` for a decent PATH default if none is found
* logs are unbuffered for cases where debug logs appear empty (exit
without handlers moment)
* chore: one-time evaluate certain makefile vars
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Co-authored-by: grialion <48643945+grialion@users.noreply.github.com>
