environment: Use full paths in gn targets

Use full paths for --virtualenv-gn-target arguments.

Tested at https://ci.chromium.org/swarming/task/51ed6ff45f233410

Change-Id: I907e819fa37fa9f8e15ee5e1e6b690526703304f
Bug: 325
Reviewed-on: https://pigweed-review.googlesource.com/c/infra/recipes/+/33721
Pigweed-Auto-Submit: Rob Mohr <mohrr@google.com>
Reviewed-by: Armando Montanez <amontanez@google.com>
Commit-Queue: Rob Mohr <mohrr@google.com>
3 files changed
tree: b324d5f6e4b7ec1c50b163c6f16f95f3e7d84eab
  1. infra/
  2. recipe_modules/
  3. recipes/
  4. .gitignore
  5. .style.yapf
  6. recipes.py