The comment incorrectly was missing the _autogen suffix.

Bug: angleproject:2621
Change-Id: Iaeb1bc5b8a1b7174e6c3699162720e0e77eff667
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2552773
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Cody Northrop <cnorthrop@google.com>