We don't start timing until after the first frame finished rendering
and is presented, so the frame count has to be 0 at that point.

Change-Id: Ic242bb5625c6c50694e7625008565ee421859624
Reviewed-on: https://swiftshader-review.googlesource.com/12488Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>