customize: deprecate package

As described in the buildroot dev day report, using a post-build script
is nowadays the preferred way of adding stuff to the rootfs.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/customize/Config.in

@@ -1,5 +1,6 @@
 config BR2_PACKAGE_CUSTOMIZE
 	bool "customize"
+	depends on BR2_DEPRECATED
 	help
 	  Add custom stuff to your buildroot.