Port MSVC specific Waf compilation flags to CMake and remove dynamic dependence to msvcr100.dll on Windows

The '/MT' and '/MTd' flags replace the dynamic link to 'msvcr100.dll' with a static link to 'libcmt.lib'. This has the nice effect to ease the deployment of libgit2 by removing the dependence on 'msvcr100.dll' which is not deployed by default on Windows.