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/compton.c

@@ -23,6 +23,7 @@
 
 #include <ev.h>
 
+#include "common.h"
 #include "compiler.h"
 #include "compton.h"
 #ifdef CONFIG_OPENGL
@@ -35,6 +36,9 @@
 #include "string_utils.h"
 #include "render.h"
 #include "utils.h"
+#include "region.h"
+#include "types.h"
+#include "c2.h"
 #include "kernel.h"
 #include "vsync.h"
 #include "log.h"