[stable] core.stdc.stdint: Fix some aliases for Windows/MSVC

[kinke]

In VS 2017's stdint.h, int32_t is a typedef for int, not long; also verifiable on MSDN (incl. VS 2015). I haven't checked DMC for conformance.

This also fixes one part of issue 19249.

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[kinke]

This was changed to long with v2.081 and used to be int before as well: 7a8eb71#diff-df39fc276ac38eb843643ec77b93a975

[TurkeyMan]

O_o ... wow, wild ;)

[PetarKirov]

Well this fails on Win32...

[PetarKirov]

I think the correct fix would be to split Win32 on DMC vs MSVC.

[TurkeyMan]

I'm surprise it's not already that way..

[kinke]

I'm surprise it's not already that way..

Yeah, me too, but no wonder - I hate these crappy mangling tests using a hardcoded mangle:

static assert(int32.mangleof == "?int32@@YAXJ@Z");

Proper tests consist in a .cpp and a .d file and really make sure they can be linked...

[kinke]

I have 2 follow-up fixes for int_fast8_t on Win64 and [u]int_fast{8,16,32}_t on FreeBSD, which would currently break compilable/teststdint.d and require dlang/dmd#8729, which in turn requires those druntime fixes to get green.
@ZombineDev: How do you guys usually handle that chicken-and-egg problem?

[dnadlinger]

For isolated tests like this, it's probably easiest to disable the failing tests in a preparatory PR, and then add them back once the fix is in.