Install hwids in /usr/lib/systemd/boot/hwids/<EFI_ARCH>/

These are meant to ship with ukify, in the same package,
so install them when ukify is enabled. Given they are
hardware-specific, use a per-arch subdirectory to make it
easier to enable them by default in ukify.

src/boot/meson.build

@@ -35,6 +35,9 @@ if conf.get('ENABLE_UKIFY') == 1
                            meson.current_source_dir()/'hwids/test'],
                 capture : true,
                 build_by_default : want_tests != 'false')
+        install_subdir('hwids',
+                       install_dir : libexecdir / 'boot/',
+                       exclude_directories : ['test'])
 else
         test_hwids_section_c = []
 endif