[gnome-icon-theme-symbolic] install-data-hook fix by Yanko Kaneti <yaneti declera com>

[Jakub Steiner <jimmac src gnome org>]

commit 84e38b44e550eac724171534a217effc0d63ca68
Author: Jakub Steiner <jimmac gmail com>
Date:   Tue Dec 21 01:22:28 2010 +0100

    install-data-hook fix by Yanko Kaneti <yaneti declera com>

 Makefile.am |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index bdbcec4..7ba0f00 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -19,7 +19,9 @@ install-data-local:
 	fi
 
 install-data-hook:
-	$(GTK_UPDATE_ICON_CACHE) -q $(DESTDIR)$(themedir)
+	if test -z "$(DESTDIR)" ; then \
+		$(GTK_UPDATE_ICON_CACHE) -q $(DESTDIR)$(themedir); \
+	fi
 
 EXTRA_DIST = gnome