Improve the include situation

Slightly clean up header inclusion with the help of clang's module system.
It's better for files to include the things you need directly.

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

src/render.h

@@ -3,7 +3,7 @@
 #pragma once
 
 #include <xcb/render.h>
-#include <xcb/xcb_image.h>
+#include <stdbool.h>
 #include "region.h"
 
 typedef struct _glx_texture glx_texture_t;