Read the values from machine-info file and expose them on D-Bus.

With meson now available there's no need to keep this around. Remove it.

The runscript shebang is deprecated, so use openrc-run instead.

The /etc/dbus-1/system.d/ path is deprecated for a while for
system-installed packages and /usr/share/dbus-1/system.d/ should be used
now.

The autotools build system uses "-include ./config.h" which makes the
macros defined in config.h available already without including config.h
directly. But for meson build system this isn't the case so we need to
move config.h before any #if that we have below.

Remove unused label and remove double assignment of entry variable.

We check in guess_icon_name for the configured chassis so we must set
the chassis value first.

Convert the existing guess_icon_name method to guess the chassis value
and build the icon name based on that.

Previously if the existing file didn't end with a newline then two shell
entries would be written without any separator to the file leading to a
broken file.

Otherwise the timezone couldn't be read correctly by users other than root

Previously we always tried to write the contents of the file in
/usr/share/zoneinfo to /etc/localtime, but that doesn't work if it
doesn't exist or if /etc/localtime is a symlink. As such, we should just
make it a symlink if it doesn't exist or already is one.

Additionally the AC_SUBST call isn't needed since Autotools v0.24

The "mv" resulted in a race condition. To avoid it, before running gdbus
codegen, switch to the directory where we want its output files to go.

The ability to set openrc-settingsd's rc status is useful mainly for
dbus activation, so a dbus-activated process can be easily stopped via
"/etc/init.d/openrc-settingsd stop".