Fix MSVC warnings in stores.cpp

[obligaron]

This PR reduces warnings by 4 (from 17 to 13).

I thought about doing more refactoring... but stores.cpp needs a more general approach.

Now only mpq_writer and mpq_sdl_rwops is missing. And there I'm unsure if I should change everything size related to size_t, uint32_t or uintmax_t. 😁

[AJenbo]

Store needs a rewrite, it's a mess :/

[AJenbo]

Now only mpq_writer and mpq_sdl_rwops is missing. And there I'm unsure if I should change everything size related to size_t, uint32_t or uintmax_t. 😁

Since it's dealing with files I would have thought size_t would be the right option

[obligaron]

Since it's dealing with files I would have thought size_t would be the right option

It's also complicated...

libmpq has

/* file offset data type for API*/
typedef int64_t libmpq__off_t;

SDL SDL_RWops needs

#ifndef USE_SDL1
using OffsetType = Sint64;
using SizeType = size_t;
#else
using OffsetType = int;
using SizeType = int;
#endif

🤔

[AJenbo]

Mmm, I see what you are saying. Well if it's any help SDL1 is the fall back so it should have all the ugly casts and we should go with what SDL2 preferes when that comes up.