overlay: introduced $overlay_apply_dirs, applied at postmake/6

lib/overlay/parse-config-0

@@ -1,8 +1,8 @@
 # --- SDE-COPYRIGHT-NOTE-BEGIN ---
 # This copyright note is auto-generated by ./scripts/Create-CopyPatch.
 #
-# Filename: lib/overlay/parse-config
-# Copyright (C) 2008 The OpenSDE Project
+# Filename: lib/overlay/parse-config-0
+# Copyright (C) 2008 - 2012 The OpenSDE Project
 #
 # More information can be found in the files COPYING and README.
 #
@@ -13,3 +13,14 @@
 # --- SDE-COPYRIGHT-NOTE-END ---
 
 . "$base/lib/overlay/overlay-functions.in"
+
+overlay_apply_dirs=
+
+overlay_apply_hook() {
+	local d=
+	for d in $overlay_apply_dirs; do
+		[ -d "$d" ] || continue
+		overlay_apply -q -- "$d"
+	done
+}
+hook_add postmake 6 'overlay_apply_hook'