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>
Moved:
* Blur kernel related functions to kernel.c
* Vsync related functions to vsync.c
* paint related functions to render.c
This will make the `split-backend` branch easier to rebase.
Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
