meson: move systemd-sysupdate to /usr/bin/

Let's make systemd-sysupdate easy to call. It was added in 2021
and it's around to stay and not "experimental" in any way.

src/sysupdate/meson.build

@@ -21,7 +21,7 @@ systemd_updatectl_sources = files(
 )
 
 executables += [
-        libexec_template + {
+        executable_template + {
                 'name' : 'systemd-sysupdate',
                 'public' : true,
                 'conditions' : ['ENABLE_SYSUPDATE'],
@@ -57,3 +57,10 @@ if conf.get('ENABLE_SYSUPDATED') == 1
         install_data('org.freedesktop.sysupdate1.policy',
                      install_dir : polkitpolicydir)
 endif
+
+if conf.get('ENABLE_SYSUPDATE') == 1
+        # symlink for backwards compatibility after rename
+        install_symlink('systemd-sysupdate',
+                        pointing_to : libexecdir_to_bin / 'systemd-sysupdate',
+                        install_dir : libexecdir)
+endif