include/feeds.mk: base list of enabled feeds on available instead of installed feeds

This fixes handling of CONFIG_FEED_* options for uninstalled feeds.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>

include/feeds.mk

@@ -10,7 +10,7 @@
 
 FEEDS_INSTALLED:=$(notdir $(wildcard $(TOPDIR)/package/feeds/*))
 FEEDS_AVAILABLE:=$(sort $(FEEDS_INSTALLED) $(shell $(SCRIPT_DIR)/feeds list -n))
-FEEDS_ENABLED:=$(foreach feed,$(FEEDS_INSTALLED),$(if $(CONFIG_FEED_$(feed)),$(feed)))
+FEEDS_ENABLED:=$(foreach feed,$(FEEDS_AVAILABLE),$(if $(CONFIG_FEED_$(feed)),$(feed)))
 FEEDS_DISABLED:=$(filter-out $(FEEDS_ENABLED),$(FEEDS_AVAILABLE))
 
 PACKAGE_SUBDIRS=$(PACKAGE_DIR)