Since it's setting two files at a time, let's simplify the function a
bit, and make use of g_auto macros. This has the additional purpose
that we want to stop failing if the timezone file cannot be set, so
this is additionally a preparation commit for that.

This is a huge simplification over previous code.
g_time_zone_new_identifier takes care of reading localtime and
fallsback to the timezone file if that does not exist.

Since it's already used twice, and will be used more in the next commits.

This is a Gentoo-only thing, that does not exist, nor is it needed in
Alpine Linux. So make it possible to not use it.

So we can get rid of the Alpine patch[1]

[1] https://git.alpinelinux.org/aports/tree/community/openrc-settingsd/use-profiled-instead-of-envd.patch

With modern openrc we can use the defaults and just set a few variables.
Also we can remove NTP_SERVICE variable since the user can set it very
easy via OPENRC_SETTINGSD_OPTS variable.

Stop using compiled-in location for pidfile, and instead pass path to
pidfile on the command line. If nothing is passed, we won't create a
pidfile.

Only Gentoo seems to use the /etc/conf.d/hostname style, implement
support for the more standard /etc/hostname.

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