Fix double-free in tapdisk cleanup

diff -r 58aa2447f212 tools/blktap/drivers/tapdisk.c
@@ -849,6 +849,8 @@ int main(int argc, char *argv[])
 		exit(-1);
 	}
 
+	DPRINTF("running R: '%s' W: '%s'\n", argv[1], argv[2]);
+
 	while (run) 
         {
 		ret = 0;

@@ -914,12 +916,13 @@ int main(int argc, char *argv[])
 		s = ptr->s;
 
 		unmap_disk(s);
-		free(s->blkif);
-		free(s->ring_info);
-		free(s);
+
 		close(ptr->tap_fd);
 		ptr = ptr->next;
 	}
+
+	DPRINTF("done R: '%s' W: '%s'\n", argv[1], argv[2]);
+
 	closelog();
 
 	return 0;