copyright: add Loongson into AUTHORS
copyright: add Loongson into AUTHORS

Contributors to the loong64 port are:
  Weining Lu <luweining@loongson.cn>
  Lei Wang <wanglei@loongson.cn>
  Lingqin Gong <gonglingqin@loongson.cn>
  Xiaolin Zhao <zhaoxiaolin@loongson.cn>
  Meidan Li <limeidan@loongson.cn>
  Xiaojuan Zhai <zhaixiaojuan@loongson.cn>
  Qiyuan Pu <puqiyuan@loongson.cn>
  Guoqi Chen <chenguoqi@loongson.cn>

This port has been updated to Go 1.15.6:
  https://github.com/loongson/go

Updates #46229

Change-Id: I23fb430f1f6e8a587f13e2f020721cbd3a45d4ed
Reviewed-on: https://go-review.googlesource.com/c/go/+/342303
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
Trust: Cherry Mui <d62e63aa42ce272d7b6a5055d97e942b33a34679@google.com>

nawawi/go,nawawi/go,golang/go,golang/go,golang/go,golang/go,golang/go,CAFxX/go,CAFxX/go,CAFxX/go,CAFxX/go,golang/go,nawawi/go,nawawi/go,golang/go,CAFxX/go,CAFxX/go,CAFxX/go,nawawi/go,CAFxX/go,nawawi/go,nawawi/go,nawawi/go,golang/go