buildGoPackage: remove Go deps file libs.json

After #16017 there were a lot
of comments saying that `nix` would be better than `JSON`
for Go packages dependency sets.
As said in https://github.com/NixOS/nixpkgs/pull/16017#issuecomment-229624046

    > Because of the content-addressable store, if two programs have the
    > same dependency it will already result in the same derivation in
    > the
    > store. Git also has compression in the pack files so it won't make
    > much difference to duplicate the dependencies on disk. And finally
    > most users will just use the binary builds so it won't make any
    > differences to them.

This PR removes `libs.json` file and puts all package dependencies in
theirs `deps.json`.

pkgs/servers/gotty/deps.json

@@ -1,15 +1,74 @@
 [
-  {
-    "include": "../../libs.json",
-    "packages": [
-      "github.com/kr/pty",
-      "github.com/braintree/manners",
-      "github.com/codegangsta/cli",
-      "github.com/elazarl/go-bindata-assetfs",
-      "github.com/fatih/structs",
-      "github.com/gorilla/websocket",
-      "github.com/hashicorp/hcl",
-      "github.com/hashicorp/go-multierror"
-    ]
-  }
+    {
+        "goPackagePath": "github.com/gorilla/websocket",
+        "fetch": {
+            "type": "git",
+            "url": "https://github.com/gorilla/websocket",
+            "rev": "a622679ebd7a3b813862379232f645f8e690e43f",
+            "sha256": "1nc9jbcmgya1i6dmf6sbcqsnxi9hbjg6dz1z0k7zmc6xdwlq0y4q"
+        }
+    },
+    {
+        "goPackagePath": "github.com/kr/pty",
+        "fetch": {
+            "type": "git",
+            "url": "https://github.com/kr/pty",
+            "rev": "67e2db24c831afa6c64fc17b4a143390674365ef",
+            "sha256": "1l3z3wbb112ar9br44m8g838z0pq2gfxcp5s3ka0xvm1hjvanw2d"
+        }
+    },
+    {
+        "goPackagePath": "github.com/braintree/manners",
+        "fetch": {
+            "type": "git",
+            "url": "https://github.com/braintree/manners",
+            "rev": "cab36f97339b1925cd89e158632728025557e550",
+            "sha256": "1q508c62iiklghkhwqz9c0zsn9hrij7kqb93gdywzj7ms7x6hlfh"
+        }
+    },
+    {
+        "goPackagePath": "github.com/codegangsta/cli",
+        "fetch": {
+            "type": "git",
+            "url": "https://github.com/codegangsta/cli",
+            "rev": "71f57d300dd6a780ac1856c005c4b518cfd498ec",
+            "sha256": "1fxznirkvank5461789dm5aw5z8aqi0jvwligvz44659rfl376p3"
+        }
+    },
+    {
+        "goPackagePath": "github.com/elazarl/go-bindata-assetfs",
+        "fetch": {
+            "type": "git",
+            "url": "https://github.com/elazarl/go-bindata-assetfs",
+            "rev": "d5cac425555ca5cf00694df246e04f05e6a55150",
+            "sha256": "636ce247ff6f85c14f38a421f46662fa77bdc29762692e1f72b3cd1f9d7a1d17"
+        }
+    },
+    {
+        "goPackagePath": "github.com/fatih/structs",
+        "fetch": {
+            "type": "git",
+            "url": "https://github.com/fatih/structs",
+            "rev": "a9f7daa9c2729e97450c2da2feda19130a367d8f",
+            "sha256": "0pyrc7svc826g37al3db19n5l4r2m9h1mlhjh3hz2r41xfaqia50"
+        }
+    },
+    {
+        "goPackagePath": "github.com/hashicorp/hcl",
+        "fetch": {
+            "type": "git",
+            "url": "https://github.com/hashicorp/hcl",
+            "rev": "54864211433d45cb780682431585b3e573b49e4a",
+            "sha256": "07l2dydzjpdgm2d4a72hkmincn455j3nrafg6hs3c23bkvizj950"
+        }
+    },
+    {
+        "goPackagePath": "github.com/hashicorp/go-multierror",
+        "fetch": {
+            "type": "git",
+            "url": "https://github.com/hashicorp/go-multierror",
+            "rev": "56912fb08d85084aa318edcf2bba735b97cf35c5",
+            "sha256": "0s01cqdab2f7fxkkjjk2wqx05a1shnwlvfn45h2pi3i4gapvcn0r"
+        }
+    }
 ]