[Bug go/123293] go: add an option to ignore "imported and not used" and "declared but not used" errors

[ian at airs dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123293

--- Comment #4 from Ian Lance Taylor <ian at airs dot com> ---
It's the same justification. I understand that you disagree. I understand that
you are only asking for a compiler option. However, this is a guideline that Go
has followed from the beginning, and we aren't going to change it now.