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/opengl.c

@@ -12,6 +12,7 @@
 #include "compiler.h"
 #include "string_utils.h"
 #include "log.h"
+#include "config.h"
 
 #include "opengl.h"