Multiple updates.

- Further configuration of the compiler flags for the Win32 builds.
- Minor rename of some symbols of WmiGpuInfoSet class.
- First implementation of the WmiGpuInfoSet class.
Multiple updates.

- The set of WmiGpuInfo instances is now a WmiGpuInfo**.
- Updated the WmiGpuInfoSet interface due to the above change.
- First implementation of the query_wmi() function.