sleeping vs sched_yield

[Chris Katko]

there's:

```d
   import core.thread;
   Thread.sleep( dur!("msecs")(10) );
```

but what if you want to simply yield all remaining time back to 
the time scheduler?

Is there a D std.library accessible version of POSIX sched_yield:

   https://man7.org/linux/man-pages/man2/sched_yield.2.html


It seems I can (thanks to the amazing work of D community) simply 
do:

```d
extern(C) int sched_yield(void);  // #include <sched.h>
```

however, how does the linker know I need <sched.h> and not some 
local library, or SDL library, or SDL2.0 library, etc. Shouldn't 
I be specifying the library somewhere?





Side side question: The above line fails to compile as-is because 
it has (void) instead of ().

```
source/app.d(226,16): Error: cannot have parameter of type `void`
```

Should that be corrected in the compiler? Shouldn't () and (void) 
be interchangeable as long as you're not doing void*?