stdint.h is C99 and while I'd love to believe that every C compiler is C99 capable by now, I don't know if that is actually the case.
Does stdint.h exist on Win32 these days?
IMHO, of course.
* no variable-length arrays
* no qualifiers in parameter array declarators (`int x[static 10]`, etc.)
* no `restrict` keyword
* no compound literals
* no designated initializers
There's probably more.
On the web you'll find the same quote copy & pasted over and over saying that support for compound literals and designated initializers was supposedly added in VS2013, but it does not appear to be true. Either that, or I haven't found the hidden switch to enable it. By the way, C code still needs to be compiled as C++ to get anything beyond C89 to work, which should give you a clue as to how serious Microsoft is about C99.
What's true though is that stdbool.h was added. It's a start, I guess...