Checking specifically for /proc/net/pfkey is not ideal as af_key will
eventually be removed in Linux kernels. Support for KLIPS is long gone.
The detection also wasn't used for anything anymore (failures were just
ignored since the ports to BSD-based systems). And modprobing doesn't seem
to be necessary either (charon-systemd doesn't do that, for instance).
Since the removal of pluto this is quite superfluous. The flag itself
might be useful to avoid starting charon if the executable does not
exist for some reason (e.g. if DAEMON_NAME is incorrect).
The parser simply returns key/value pairs of all sections, it already
resolves also= and allows overriding options in all included sections
(not only %default), options set in included section can also be cleared
again (key=).
It provides other improvements too, like quoted strings (with escape
sequences), unlimited includes and better whitespace/comment handling.
Because all packages are now marked as optional executables that are to
be installed on the final system have to be added to PRODUCT_PACKAGES in
build/target/product/core.mk. Dependencies (such as libraries) are
installed automatically.
