abuild: use APKINDEX.tar.gz rather than APK_INDEX.gz

abuild.in

@@ -465,6 +465,7 @@ apkcache() {
 	if ! apk_up2date || [ -n "$force" ]; then
 		sanitycheck && builddeps && clean && fetch && unpack && rootpkg || return 1
 	fi
+
 	local apk
 	mkdir -p "$apkcache" || return 1
 	cd "$apkcache"
@@ -610,7 +611,7 @@ cache_up2date() {
 	local i apk
 	for i in $pkgname $subpackages; do
 		apk="${i%:*}-$pkgver-r$pkgrel.apk"
-		[ "$apkcache"/APK_INDEX.gz -nt "$apkcache"/$apk ] || return 1
+		[ "$apkcache"/APKINDEX.tar.gz -nt "$apkcache"/$apk ] || return 1
 	done
 	return 0
 }