fixes #9872

[cc] gcc: error: unrecognized command line option '-m64'

fortify breaks build:
https://github.com/pybind/pybind11/issues/1650

Without creating /var/lib/snapserver the services fails to start with
the following error message:

	Exception: failed to create settings directory: "/var/lib/snapserver/": 13

Because the snapcast process itself tries to create the directory but
doesn't run as root and therefore gets an EACCESS (13) error.

While at it I also specified the pidfile created by the snapcast
process. No idea how OpenRC was even able to track the service status
without it.

We need the initramfs to exists when grub trigger is executed so depend
on mkintfs so the mkinitfs trigger runs before grub trigger.