build: allow creating empty package feeds

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

SVN-Revision: 45757

package/Makefile

@@ -138,8 +138,8 @@ endif
 $(curdir)/index: FORCE
 	@echo Generating package index...
 	@for d in $(PACKAGE_SUBDIRS); do ( \
-		[ -d $(PACKAGE_DIR)/$$d ] && \
-			cd $(PACKAGE_DIR)/$$d || continue; \
+		mkdir -p $(PACKAGE_DIR)/$$d; \
+		cd $(PACKAGE_DIR)/$$d || continue; \
 		$(SCRIPT_DIR)/ipkg-make-index.sh . 2>&1 > Packages && \
 			gzip -9c Packages > Packages.gz; \
 	); done