Adjust check for outdated triggers file

With the switch to jinja2, the file is generated during normal build, so
we need to move the check later.

systemd.spec

@@ -521,6 +521,8 @@ CONFIGURE_OPTS=(
 %endif
 { %meson "${CONFIGURE_OPTS[@]}"; }
 
+%meson_build
+
 new_triggers=%{_vpath_builddir}/src/rpm/triggers.systemd.sh
 if ! diff -u %{SOURCE1} ${new_triggers}; then
    echo -e "\n\n\nWARNING: triggers.systemd in Source1 is different!"
@@ -528,8 +530,6 @@ if ! diff -u %{SOURCE1} ${new_triggers}; then
    sleep 5
 fi
 
-%meson_build
-
 %install
 %meson_install