Small compilation problems in Mingw-w64

[thomask77]

Hi!

I'm using MSYS2 / mingw-w64 and have 3 minor issues when building with either GCC or clang.

Steps to reproduce:

• Install MSYS2

pacman -Syu mingw-w64-x86_64-clang
pacman -Syu mingw-w64-x86_64-cmake
pacman -Syu mingw-w64-x86_64-ninja

# clang version 10.0.1 (https://github.com/Alexpux/MINGW-packages.git 94b687508346d10cec7e8c769785f73da18b4e54)
# Target: x86_64-w64-windows-gnu
# Thread model: posix
# InstalledDir: C:\msys64\mingw64\bin

mkdir build && cd build
CC=clang CXX=clang++ cmake .. -G"Ninja"
ninja

1st problem:

_deps/mahi-gui-src/src/Mahi/Gui/nanovg_custom.cpp:14:12: error: no member named 'memcpy' in namespace 'std'; did you mean 'wmemcpy'?
using std::memcpy;
      ~~~~~^~~~~~
           wmemcpy
C:\msys64\mingw64\include\c++\10.2.0\cwchar:201:11: note: 'wmemcpy' declared here
  using ::wmemcpy;
          ^
1 error generated.

2nd problem:

_deps/mahi-gui-src/src/Mahi/Gui/Application.cpp:24:12: error: no member named 'memcpy' in namespace 'std'; did you mean 'wmemcpy'?
using std::memcpy;
      ~~~~~^~~~~~
           wmemcpy
C:\msys64\mingw64\include\c++\10.2.0\cwchar:201:11: note: 'wmemcpy' declared here
  using ::wmemcpy;
          ^
1 error generated.

-> Both are easily fixed by adding #include <cstring>

3rd problem:

_deps/mahi-util-src/src/Mahi/Util/System.cpp:344:15: error: no member named 'GetFileVersionInfoSizeExW' in the global namespace
            ::GetFileVersionInfoSizeExW(FILE_VER_GET_NEUTRAL, system, &dummy);
            ~~^
_deps/mahi-util-src/src/Mahi/Util/System.cpp:344:41: error: use of undeclared identifier 'FILE_VER_GET_NEUTRAL'
            ::GetFileVersionInfoSizeExW(FILE_VER_GET_NEUTRAL, system, &dummy);
                                        ^
_deps/mahi-util-src/src/Mahi/Util/System.cpp:346:11: error: no member named 'GetFileVersionInfoExW' in the global namespace
        ::GetFileVersionInfoExW(FILE_VER_GET_NEUTRAL, system, dummy, (DWORD)buffer.size(), &buffer[0]);
        ~~^
_deps/mahi-util-src/src/Mahi/Util/System.cpp:346:33: error: use of undeclared identifier 'FILE_VER_GET_NEUTRAL'
        ::GetFileVersionInfoExW(FILE_VER_GET_NEUTRAL, system, dummy, (DWORD)buffer.size(), &buffer[0]);
                                ^
4 errors generated.

I fixed this by using the non-ex variants GetFileVersionInfoSizeW and GetFileVersionInfoW and omitting the FILE_VER_GET_NEUTRAL flag.

The demo application runs fine after these fixes (with both GCC, clang and make or Ninja as a build Tool).

Should I send a pull request, or could you implement and test those fixes yourself?

I'm unsure about the 3rd point. What's the reason for FILE_VER_GET_NEUTRAL?