build-sys: the pure/const warning options are probably too much as default, but let's make it available via "autogen.sh a"
build-sys: minor fixes found with cppcheck
Revert "journalctl: remove unexpected behavior of journalctl -b"

This reverts commit cf5bccc2bb9569030cb04debbc4208aaca0fe5b4.

We should fix thinks properly if they aren't perfect, not just break
other things...
Revert "completion: don't offer completions for journalctl -b"

This reverts commit c756a6d57cdb678b702c68913dae3e11ff0427ae.
journalctl: make sure -b --foobar cannot be misunderstood as --boot=--foobar