pdfcrack is cross platform now

Bases on PDFCrack 0.19, I add Windows support, and tested on Windows 10, Ubuntu 20.04 and macOS 10.15.5 (19F101), all succeed.

please visit pdfcrack@Github to get the last version source code.

btw, I also offer Windows 64-bit and macOS 64-bit version.

I am not familiar with c/c++, if you find any issue, feel free to open a issue.