- Add initial device-side build configuration for LLVM7
- Made platform headers module available everywhere (host, device+core, device+vendor)
- Added missing source files from src/Vulkan/*
- Adjusted SPIRV-Tools build to be available to vendor code, and static only
  (otherwise we end up with a .so for it in the vendor image)

Bug: b/122837488
Change-Id: I9be0eaf91c90a6967fe9d3f8350c94c530f61122
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/28409Tested-by: Chris Forbes <chrisforbes@google.com>
Presubmit-Ready: Chris Forbes <chrisforbes@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Greg Hartman <ghartman@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>