gtk+: fixed gtk-icon-cache postinstall to the case where XDG_DATA_DIRS is empty

gtk+/gtk+/gtk-icon-cache.postinstall

@@ -3,6 +3,7 @@
 # This copyright note is auto-generated by ./scripts/Create-CopyPatch.
 #
 # Filename: package/.../gtk+/gtk-icon-cache.postinstall
+# Copyright (C) 2009 The OpenSDE Project
 # Copyright (C) 2004 - 2006 The T2 SDE Project
 #
 # More information can be found in the files COPYING and README.
@@ -13,7 +14,7 @@
 # GNU General Public License can be found in the file COPYING.
 # --- SDE-COPYRIGHT-NOTE-END ---
 
-set ${XDG_DATA_DIRS//:/ }
+set -- ${XDG_DATA_DIRS//:/ }
 for dir; do
 	echo "Caching icons for GNOME in $dir/icons/* ..."
 	gtk-update-icon-cache $dir/icons/*/