Some changes for better use of postinstall_helpers and run_stuff_*.

Introduce run_stuff_<state>_<stage>_cmd. These are used to run
a specific command before or after the specified stage.

Introduce two new helpers: fontconfig-update.sh and mkfontxx-rebuild.sh.
The first runs fc-cache once fontconfig is installed, the second
rebuilds the fonts.dir and fonts.scale files in a directory for
a template.

Allow run_stuff_* to execute a script with any path, not just
from PKGFS_TEMPLATESDIR.

That means that now if you install GTK+ and any fonts package,
gtk-demo will work without any additional stuff.

--HG--
extra : convert_revision : c8aa7eb8d1ab958f64808af0d4c1cce8760d012e

templates/font-adobe-75dpi.tmpl

@@ -17,3 +17,8 @@ long_desc="
   - Times
 
  This is from the modular Xorg project."
+
+# Build fonts.dir and fonts.scale files after install.
+fonts_dir="$PKGFS_MASTERDIR/lib/X11/fonts/100dpi"
+postinstall_helpers="mkfontxx-rebuild.sh"
+ignore_files="fonts.scale fonts.dir"