include/feeds.mk: allow installation from feed packages that are installed but no longer in feeds.conf

Signed-off-by: Felix Fietkau <nbd@nbd.name>

include/feeds.mk

@@ -8,8 +8,8 @@
 
 -include $(TMP_DIR)/.packagesubdirs
 
-FEEDS_AVAILABLE:=$(shell $(SCRIPT_DIR)/feeds list -n)
 FEEDS_INSTALLED:=$(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)),$(feed)))
 FEEDS_DISABLED:=$(filter-out $(FEEDS_ENABLED),$(FEEDS_AVAILABLE))