NVIDIA Shield do not implement Vulkan, which is used to populate
vendor IDs in SystemInfo. The vendorIDs are used to check IsNVIDIA().
This CL adds a workaround so IsNVIDIA() returns true for NVIDIA
Shield.

Bug: angleproject:3541
Change-Id: Ib36dd376207163acfc8d3a0e341f07a7d6aa3122
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1663080
Commit-Queue: Jonah Ryan-Davis <jonahr@google.com>
Reviewed-by: Geoff Lang <geofflang@chromium.org>