abuild: display error for unsupported archives

abuild

@@ -163,6 +163,9 @@ unpack() {
 			*.zip)
 				msg "Unpacking $s..."
 				unzip "$s" -d "$srcdir" || return 1;;
+			*)
+				error "Archive not supported"
+				return 1;;
 		esac
 	done
 }