add windows file extensions in meson_post_install.py in case it's compiling for windows.

[Kreijstal]

Please submit only one feature request in one issue!

Basically when running the python script from meson, it attempts to run some executables that can't be found because it executes them without the file extension,

Describe the solution you'd like add a check to see if it's running on windows, and conditionally add the extension.

Describe alternatives you've considered I guess you could also detect to see if you're on windows and use some other python script like meson_post_install.windows.py conditionally.

[Kreijstal]

I would also like to add that DATA_DIR is hardcoded instead of using meson's datadir because the user could have always changed the value of datadir it's not necesarily in prefix/'share'...

[flxzt]

should be fixed with #235