Require `stdint.h` & `inttypes.h`

Require `stdint.h` & `inttypes.h`

With #1450 which goes with 480cc9d49775d018c19ce0e01f6be27858d63d39 "Remove support for non-C99 compilers (like VS2010) that don't support snprintf()",
support for MSVC versions prior to vs2015 is dropped: https://stackoverflow.com/questions/2915672/snprintf-and-visual-studio-2010

This means that all supported MSVC versions do have `stdint.h` & `inttypes.h` now.
For non windows platforms, those headers were already mandatory.

Make them mandatory for all builds.