Use default commit.h file if git index is not available The solution is the same as in GYP version: 1. Check if .git/index is available in angle directory. 2. Use generated commit.h file if git is available or copy the default file instead. Change-Id: Ic3cedf6793c368070228a63c0eb270ca6fb47f81 Reviewed-on: https://chromium-review.googlesource.com/289391 Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Tomasz Moniuszko <tmoniuszko@opera.com>