Remove win_vulkan_sdk.

We only needed this for the Vulkan headers, which we now have in
src/third_party.

Change-Id: I453ed73c73b3304520b628527102607d848bcd37
Reviewed-on: https://skia-review.googlesource.com/c/180775
Commit-Queue: Greg Daniel <egdaniel@google.com>
Auto-Submit: Ben Wagner <benjaminwagner@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
11 files changed