instead of having one simple per-file cache implement an more
comprehensive one that works for multiple files and can actually
maintain multiple maps per file and per object type.
This adds forward-secure authentication of journal files. This patch
includes key generation as well as tagging of journal files,
Verification of journal files will be added in a later patch.
The default of 2047 hash table entries turned out to result in way too
many collisions for bigger files, hence scale the hash table size by the
estimated maximum file size.
We finally got the OK from all contributors with non-trivial commits to
relicense systemd from GPL2+ to LGPL2.1+.
Some udev bits continue to be GPL2+ for now, but we are looking into
relicensing them too, to allow free copy/paste of all code within
systemd.
The bits that used to be MIT continue to be MIT.
The big benefit of the relicensing is that closed source code may now
link against libsystemd-login.so and friends.
