We don't actually need the SDK to build anymore.
If you previously set skia_vulkan_sdk or relied on VULKAN_SDK
in the environment, now set skia_use_vulkan = true instead.
We still need the linux_vulkan_sdk asset for Test/Perf bots.
Change-Id: I70ad9c5181ae61725b9dc25cc887dd0640beeed6
Reviewed-on: https://skia-review.googlesource.com/c/184065
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
98dea7b11c