bin/xbps-install/transaction: print consistently for dry run

this ensures there will always be 6 fields per line, making it possible
to parse the output consistently. `arch` and `repository` default to `-`.
`installed_size` and `filename-size` default to 0 to allow for easy
tabulation.

bin/xbps-install/transaction.c

@@ -64,12 +64,12 @@ show_actions(xbps_object_iterator_t iter)
 		xbps_dictionary_get_cstring_nocopy(obj, "architecture", &arch);
 		if (repoloc && arch)
 			printf(" %s %s", arch, repoloc);
+		else
+			printf(" - -");
 		xbps_dictionary_get_uint64(obj, "installed_size", &isize);
 		xbps_dictionary_get_uint64(obj, "filename-size", &dsize);
-		if (isize)
-			printf(" %ju", isize);
-		if (dsize)
-			printf(" %ju", dsize);
+		printf(" %ju", isize);
+		printf(" %ju", dsize);
 
 		printf("\n");
 	}