linux/sdl_v4l_video: support musl
linux/sdl_v4l_video: support musl

musl C library uses a definition of ioctl with signed int which causes
-Woverflow to trigger when using read ioctl opcodes.

fishilico/shared,fishilico/shared,fishilico/shared,fishilico/shared,fishilico/shared,fishilico/shared,fishilico/shared