eclass/golang-vcs-snapshot: Sync with gentoo

It's from gentoo commit 7f8297d319da8a7fe6680217ad8362b46ac1c95a.

eclass/golang-vcs-snapshot.eclass

@@ -1,12 +1,13 @@
-# Copyright 1999-2015 Gentoo Foundation
+# Copyright 1999-2021 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 # @ECLASS: golang-vcs-snapshot.eclass
 # @MAINTAINER:
 # William Hubbs <[email protected]>
 # @SUPPORTED_EAPIS: 5 6 7
-# @BLURB: support eclass for unpacking VCS snapshot tarballs for
-# software written in the Go programming language
+# @PROVIDES: golang-base
+# @BLURB: eclass to unpack VCS snapshot tarballs for Go software
+# @DEPRECATED: go-module.eclass
 # @DESCRIPTION:
 # This eclass provides a convenience src_unpack() which unpacks the
 # first tarball mentioned in SRC_URI to its appropriate location in