reactivate software-based CRC32 on x64 platforms without SSE4.2
refactoring of IteratorBasedCRC32, fixes #1140
make dummy __get_cpuid available on Windows
apply some reformatting
Merge pull request #1156 from Project-OSRM/experimental/crc32_fix

reactivate software-based CRC32 on x64 platforms without SSE4.2, closes #1140