gnu: Remove go-gopkg-in-mgo-v2.

Not in use by any other packages in Guix. Unmaintained according to
project's about, see <https://github.com/go-mgo/mgo/pull/574>.

* gnu/packages/databases.scm (go-gopkg-in-mgo-v2): Delete variable.

Change-Id: Idc1e064e20a3263fc62f478bf4fe69b7b39a4dcb

gnu/packages/databases.scm

@@ -3676,34 +3676,6 @@ etc., and an SQL engine for performing simple SQL queries.")
     (license (list license:lgpl2.0
                    license:gpl2+))))
 
-(define-public go-gopkg-in-mgo-v2
-  (package
-    (name "go-gopkg-in-mgo-v2")
-    (version "2.0.0-20190816093944-a6b53ec6cb22")
-    (source
-      (origin
-        (method git-fetch)
-        (uri (git-reference
-               (url "https://gopkg.in/mgo.v2")
-               (commit (go-version->git-ref version))))
-        (file-name (git-file-name name version))
-        (sha256
-         (base32 "1lgvwxsbmdrf4938qkxl56wbwgbphk2qqnmpf73qdmlv4qsg14na"))))
-    (build-system go-build-system)
-    (arguments
-     '(#:tests? #f      ; Tests try to use a running mongodb server.
-       #:import-path "gopkg.in/mgo.v2"))
-    (propagated-inputs
-     (list go-gopkg.in-tomb.v2))
-    (inputs
-     (list cyrus-sasl))
-    (native-inputs
-     (list go-gopkg-in-check-v1))
-    (home-page "https://gopkg.in/mgo.v2")
-    (synopsis "MongoDB driver for Go")
-    (description "This package provides a MongoDB driver for Go.")
-    (license license:bsd-2)))
-
 (define-public python-lmdb
   (package
     (name "python-lmdb")