`find_program()` evaluates to `python psl-make-dafsa` on Windows, so
running it with `python` evaluates to `python python psl-make-dafsa`,
causing this error on Windows:
```
"c:/python38/python.exe" "python" "C:/projects/repos/libpsl/src/psl-make-dafsa" "--output-format=binary" "C:/projects/repos/libpsl/list/public_suffix_list.dat" "tests/psl.dafsa"
c:/python38/python.exe: can't open file 'python': [Errno 2] No such file or directory
```
We must link to ws2_32.lib for all Windows builds, and we need to use
workarounds for alloca() and snprintf() since Visual Studio uses
_alloca() for alloca() and provides snprintf() only on Visual Studio
2015 or later, meaning that we need to use _snprintf() here.
Also fix the parts where we run the Python scripts to generate items,
since those scripts already have shebang lines for Meson to pick up.
Erica Ehrhardt
Tim-Philipp Müller
Chris Hiszpanski
Tomasz Kłoczko
Nirbheek Chauhan
Matthew Waters
Ignacio Casal Quinteiro
Chun-wei Fan
Xavier Claessens