gdk-pixbuf: unbreak gdk-pixbuf loaders.cache

Fix gdk-pixbuf broken by host package moved to /lib instead of /usr/lib
Regression occured following commit 19ba17ee3ba946ac86 (Globally replace
$(HOST_DIR)/usr/lib with $(HOST_DIR)/lib).

The host package loader.cache now refer to $(HOST_DIR)/lib, and the target
one should refer to /usr/lib.

Fix it by adjusting the sed invocation.

[Peter: extend commit message]
Signed-off-by: Pierre CROKAERT <pct@crookies.net>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/gdk-pixbuf/gdk-pixbuf.mk

@@ -64,7 +64,7 @@ define GDK_PIXBUF_UPDATE_CACHE
 	GDK_PIXBUF_MODULEDIR=$(HOST_DIR)/lib/gdk-pixbuf-2.0/2.10.0/loaders \
 		$(HOST_DIR)/bin/gdk-pixbuf-query-loaders \
 		> $(TARGET_DIR)/usr/lib/gdk-pixbuf-2.0/2.10.0/loaders.cache
-	$(SED) "s,$(HOST_DIR),,g" \
+	$(SED) "s,$(HOST_DIR)/lib,/usr/lib,g" \
 		$(TARGET_DIR)/usr/lib/gdk-pixbuf-2.0/2.10.0/loaders.cache
 endef
 GDK_PIXBUF_POST_INSTALL_TARGET_HOOKS += GDK_PIXBUF_UPDATE_CACHE