We were missing a "no chromium code" config in the mock ICD.
This was causing a build error, but the build error was mostly
invisible because the mock ICD wasn't being built by default.

Fix this by including it in the angle_vulkan target.

Bug: angleproject:2482
Change-Id: I417d3fbf6a4acd93c06bab61967409730c2ea4ed
Reviewed-on: https://chromium-review.googlesource.com/1012497Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>