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/tools/system/confd/deps.json

@@ -1,15 +1,74 @@
 [
-  {
-    "include": "../../libs.json",
-    "packages": [
-      "github.com/kelseyhightower/memkv",
-      "github.com/armon/consul-api",
-      "github.com/garyburd/redigo",
-      "github.com/samuel/go-zookeeper",
-      "github.com/BurntSushi/toml",
-      "github.com/Sirupsen/logrus",
-      "github.com/coreos/go-etcd",
-      "github.com/ugorji/go"
-    ]
-  }
+    {
+        "goPackagePath": "github.com/Sirupsen/logrus",
+        "fetch": {
+            "type": "git",
+            "url": "https://github.com/Sirupsen/logrus",
+            "rev": "be52937128b38f1d99787bb476c789e2af1147f1",
+            "sha256": "1m6vvd4pg4lwglhk54lv5mf6cc8h7bi0d9zb3gar4crz531r66y4"
+        }
+    },
+    {
+        "goPackagePath": "github.com/coreos/go-etcd",
+        "fetch": {
+            "type": "git",
+            "url": "https://github.com/coreos/go-etcd",
+            "rev": "9847b93751a5fbaf227b893d172cee0104ac6427",
+            "sha256": "1ihq01ayqzxvn6hca5j00vl189vi5lm78f0fy2wpk5mrm3xi01l4"
+        }
+    },
+    {
+        "goPackagePath": "github.com/ugorji/go",
+        "fetch": {
+            "type": "git",
+            "url": "https://github.com/ugorji/go",
+            "rev": "03e33114d4d60a1f37150325e15f51b0fa6fc4f6",
+            "sha256": "01kdzgx23cgb4k867m1pvsw14hhdr9jf2frqy6i4j4221055m57v"
+        }
+    },
+    {
+        "goPackagePath": "github.com/samuel/go-zookeeper",
+        "fetch": {
+            "type": "git",
+            "url": "https://github.com/samuel/go-zookeeper",
+            "rev": "5bb5cfc093ad18a28148c578f8632cfdb4d802e4",
+            "sha256": "1kpx1ymh7rds0b2km291idnyqi0zck74nd8hnk72crgz7wmpqv6z"
+        }
+    },
+    {
+        "goPackagePath": "github.com/BurntSushi/toml",
+        "fetch": {
+            "type": "git",
+            "url": "https://github.com/BurntSushi/toml",
+            "rev": "056c9bc7be7190eaa7715723883caffa5f8fa3e4",
+            "sha256": "0gkgkw04ndr5y7hrdy0r4v2drs5srwfcw2bs1gyas066hwl84xyw"
+        }
+    },
+    {
+        "goPackagePath": "github.com/kelseyhightower/memkv",
+        "fetch": {
+            "type": "git",
+            "url": "https://github.com/kelseyhightower/memkv",
+            "rev": "7f9c7f36f45ba80c62fe22779ee78d9b4ca36580",
+            "sha256": "090x65kr3gqh8fc8z4rm9hc2r0v0k7rfm5vsbmhdh21f48ixw540"
+        }
+    },
+    {
+        "goPackagePath": "github.com/armon/consul-api",
+        "fetch": {
+            "type": "git",
+            "url": "https://github.com/armon/consul-api",
+            "rev": "f79efe463cdbb62f6d5a55f879a63ec554eb13e5",
+            "sha256": "1rkmzfhsazj9p2b6ywvs8yramzvxfxyvplzxi0ldvhcv04887gcp"
+        }
+    },
+    {
+        "goPackagePath": "github.com/garyburd/redigo",
+        "fetch": {
+            "type": "git",
+            "url": "https://github.com/garyburd/redigo",
+            "rev": "535138d7bcd717d6531c701ef5933d98b1866257",
+            "sha256": "1m7nc1gvv5yqnq8ii75f33485il6y6prf8gxl97dimsw94qccc5v"
+        }
+    }
 ]