timedated: fix a few memory leaks

Contents of /etc/adjtime and more.
efivars: un-leak a few strings
udevadm-hwdb: avoid leak in error path
sd-id128: check that the kernel is feeding us proper data

The characters are already checked, so we show that
we don't trust the kernel. Make sure we don't overrun
the buffer too.
systemctl: align cgroups to 'n' in 'name='

Also drop ':' in repeated Docs lines.
journal: u64log2 can be expressed just as __builtin_clzll(n) ^ 63U
test-catalog,core/load-dropin: remove unused variables
test-strv: do not declare table to be sorted const

Segmentation fault under clang.