dsound/tests: The tests link with dsound.dll so use GetModuleHandle() instead of LoadLibrary().

[Felix Nawothnig]

Francois Gouget wrote:
> This is a NOP, it just seems a bit cleaner to me.
> 
> -    hDsound = LoadLibraryA("dsound.dll");
> -    if (!hDsound) {
> -        trace("dsound.dll not found\n");
> -        return;
> -    }
> -
> +    hDsound = GetModuleHandleA("dsound.dll");
> +    ok(hDsound != NULL, "dsound.dll not loaded!\n");

No it's not, that causes test failure on native when DirectX is not 
installed (NT4 out-of-the-box I believe?).