compat: fix clock_nanosleep warning

In file included from /home/b1ue/nov/update/vlc/compat/clock_nanosleep.c:31:
/home/b1ue/nov/update/emsdk/upstream/emscripten/cache/sysroot/include/sys/errno.h:1:2: warning: redirecting incorrect #include <sys/errno.h> to <errno.h> [-W#warnings]
#warning redirecting incorrect #include <sys/errno.h> to <errno.h>
 ^
1 warning generated.
```