build: move append-string to image-commands.mk

Move it to image-commands.mk so that it can used by other targets.

Signed-off-by: Mathias Kresin <dev@kresin.me>

include/image-commands.mk

@@ -102,6 +102,10 @@ define Build/append-squashfs-fakeroot-be
 	cat $@.fakesquashfs >> $@
 endef
 
+define Build/append-string
+	echo -n $(1) >> $@
+endef
+
 # append a fake/empty uImage header, to fool bootloaders rootfs integrity check
 # for example
 define Build/append-uImage-fakehdr

target/linux/ar71xx/image/generic.mk

@@ -12,10 +12,6 @@ define Build/append-md5sum-bin
 		xargs echo -ne >> $@
 endef
 
-define Build/append-string
-	echo -n $(1) >> $@
-endef
-
 define Build/mkwrggimg
 	$(STAGING_DIR_HOST)/bin/mkwrggimg -b \
 		-i $@ -o $@.imghdr -d /dev/mtdblock/1 \