mkosi: Find hostname command on Arch Linux

exec-specifier.service: Executing: /usr/bin/sh -c 'test mkosi-7d5e81c7b81c42338d060a6b98edd44a = $(hostname)'
/usr/bin/sh: hostname: command not found
/usr/bin/sh: line 0: test: mkosi-7d5e81c7b81c42338d060a6b98edd44a: unary operator expected
Received SIGCHLD from PID 7389 (sh).
Child 7389 (sh) died (code=exited, status=2/INVALIDARGUMENT)

gettext provides the hostname binary, but puts it in
/usr/lib/gettext/hostname, which is not part of the default $PATH. Using
inetutils instead puts the binary in /usr/bin/hostname.

.mkosi/mkosi.arch

@@ -27,11 +27,11 @@ BuildPackages=
         docbook-xsl
         elfutils
         gcc
-        gettext
         git
         gnu-efi-libs
         gnutls
         gperf
+        inetutils
         iptables
         kmod
         libcap

TODO

@@ -17,6 +17,17 @@ Janitorial Clean-ups:
 * rework mount.c and swap.c to follow proper state enumeration/deserialization
   semantics, like we do for device.c now
 
+Before v244:
+
+* revisit SystemdOptions EFI variable. Find a better, systematic name and use
+  it for the env var, the bootctl verb and the EFI variable itself, clear up
+  semantics.
+
+* Figure out a better name for the global per-unit-type drop-in dirs, it's
+  confusing when it comes to -.mount.d/ (is it a drop-in-dir for all mount
+  units, or one for the root mount?). Also, OOM handling in
+  service_unit_name_is_valid() is borked.
+
 Features:
 
 * coredump: maybe when coredumping read a new xattr from /proc/$PID/exe that
@@ -257,9 +268,6 @@ Features:
 
 * bypass SIGTERM state in unit files if KillSignal is SIGKILL
 
-* tree-wide: ensure we always block the signals we hook into with
-  sd_event_add_signal() first
-
 * add proper dbus APIs for the various sd_notify() commands, such as MAINPID=1
   and so on, which would mean we could report errors and such.