d3dx9_36: Provide a replacement for signbit() if it is missing.

[Alexandre Julliard]

Francois Gouget <fgouget at codeweavers.com> writes:

> @@ -292,6 +292,10 @@ ssize_t pwrite( int fd, const void *buf, size_t count, off_t offset );
>  int readlink( const char *path, char *buf, size_t size );
>  #endif /* HAVE_READLINK */
>  
> +#ifndef HAVE_SIGNBIT
> +#define signbit(x) (copysign(1, (x)) < 0)
> +#endif /* !defined(HAVE_SIGNBIT) */

This isn't quite correct for floats, and it's not much more
portable. I'd suggest to fix the code instead.

-- 
Alexandre Julliard
julliard at winehq.org