Add gen_interface to CheckGeneratedFiles check

Checked that it properly fails on PS2

Change-Id: Ieff2e035a18cd5572dfe3a20a58bd760477a2b62
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/204446
Reviewed-by: Eric Boren <borenet@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
4 files changed