We no longer use the optional parameter to compareAPI.
We now always set allowAdd to false.
(Except in tests, making them less useful than they could be.)
Flags and parsing their value are no more.
Remove all the unused functionality and update test cases so they're
closer to what the API checker does when it runs for real. Order the
features, required, exception variables and fields more consistently.
For #43956.
Change-Id: Iaa4656a89a3fca3129742165a448d385e55e4a98
Reviewed-on: https://go-review.googlesource.com/c/go/+/489436
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org> Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>