Add graphics APIs to obtain the GPU driver version and renderer
strings, as well as GDDR memory sizes. The GDDR memory sizes
include the dmem (dedicated memory on the GPU) and smem
(shared CPU memory used by the GPU but resides in the CPU DDR).
The version and renderer strings are needed for identification
purposes, for example enhanced broadcasting used by Twitch, to
associate the GPU used by OBS with the PCIe-based identification
values such as device_id and vendor_id.
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