Overcome the 'GetTickCount64' issue on XP using C++11 chrono library.

For those in need of such option. I haven't tested the implementation (*although it should be fairly straight forward*). The only thing I've tested was to see if it compiles. The used compiler was [MinGW-w64 4.9.2 x32](http://sourceforge.net/projects/mingw-w64/files/Toolchains%20targetting%20Win32/Personal%20Builds/mingw-builds/4.9.2/threads-posix/dwarf/).