Untangle headers

Thanks, clang -fmodules.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/backend/driver.c

@@ -1,5 +1,7 @@
 // SPDX-License-Identifier: MPL-2.0
 // Copyright (c) Yuxuan Shui <yshuiv7@gmail.com>
+#include <stdlib.h>
+#include <string.h>
 
 #include <xcb/randr.h>
 #include <xcb/xcb.h>
@@ -7,6 +9,8 @@
 #include "backend/backend.h"
 #include "backend/driver.h"
 #include "common.h"
+#include "compiler.h"
+#include "log.h"
 
 enum driver detect_driver(xcb_connection_t *c, backend_t *backend_data, xcb_window_t window) {
 	enum driver ret = 0;