[infra/win] Add vm-kernel-precomp-win-debug-x64c to test matrix.
[infra/win] Add vm-kernel-precomp-win-debug-x64c to test matrix.

This is follow-up to https://dart-review.googlesource.com/c/sdk/+/208680.

This fixes https://ci.chromium.org/ui/p/dart/builders/ci.sandbox/vm-kernel-precomp-win-debug-x64c/2/overview errors

Change-Id: I4307206ae6da41113a9c614a291979531547acc7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/208882
Reviewed-by: Ryan Macnak <d738b7f001baf9789095d7dc549cff6de60b011d@google.com>
Commit-Queue: Alexander Aprelev <dfb74c35a357c2059971a4bf7fe26b6a7c18085d@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk