GitLab

Add a new gyp variable: use_libpci (default value is 1).
Add a new define when use_libpci==1: USE_LIBPCI.
Don't call specific PCI code in gpu_info_collector_linux.cc if USE_LIBPCI isn't defined.

BUG=427401
R=piman@chromium.org

Review URL: https://codereview.chromium.org/692893004

Cr-Commit-Position: refs/heads/master@{#302613}