Add support for other operating systems

[dbahrdt]

Maybe some users want support for other OS, like Windows. Feel free to send in patches

Hello, i have send you a pull request fixing support for Windows. Your library is great. Reading 166 MB PBF file takes only 4,7s to read with OpenMp and single thread 7,3 s which is the half time of https://github.com/CanalTP/libosmpbfreader. I haven´t tried the std::thread version, but with OpenMP it was easy to set up variable sharing for some test counting variables for how many nodes,ways and relations were read. Great job!