winmm: Fix some spec file entries

[Andrew Eikum]

On Wed, Feb 22, 2017 at 11:23:08PM +0100, André Hentschel wrote:
> -@ stdcall PlaySound(ptr long long) PlaySoundA
> -@ stdcall PlaySoundA(ptr long long)
> -@ stdcall PlaySoundW(ptr long long)
> +@ stdcall PlaySound(str long long) PlaySoundA
> +@ stdcall PlaySoundA(str long long)
> +@ stdcall PlaySoundW(wstr long long)

The first parameter is not always a string, sometimes it's a resource
identifier or even a raw pointer:

https://msdn.microsoft.com/en-us/library/windows/desktop/dd743679(v=vs.85).aspx

Andrew