Use gio-querymodules

GIO has this facility, so we should use it.
At the same time, make sure the immodules directory
exists, even if we don't install any modules there
outselves.

build-aux/meson/post-install.sh

@@ -15,4 +15,12 @@ if [ -z "$DESTDIR" ]; then
 
   echo Updating icon cache...
   gtk-update-icon-cache -q -t -f ${gtk_datadir}/icons/hicolor
+
+  echo Updating module cache for print backends...
+  mkdir -p ${gtk_libdir}/gtk-4.0/4.0.0/printbackends
+  gio-querymodules ${gtk_libdir}/gtk-4.0/4.0.0/printbackends
+
+  echo Updating module cache for input methods...
+  mkdir -p ${gtk_libdir}/gtk-4.0/4.0.0/immodules
+  gio-querymodules ${gtk_libdir}/gtk-4.0/4.0.0/immodules
 fi