go.mod, go.sum: add back in after v2 module renaming

Change-Id: Iba5d25391870b4a6014fd90fc79ab101c75ea3c7
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/177042
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>

cmd/protoc-gen-go-grpc/testdata/go.mod

@@ -1,7 +1,7 @@
 module google.golang.org/protobuf/cmd/protoc-gen-go-grpc/testdata
 
 require (
-	github.com/golang/protobuf v1.2.1-0.20190509013249-911a20d79252
+	github.com/golang/protobuf v1.2.1-0.20190514181236-7800af189d76
 	google.golang.org/grpc v1.19.0
 	google.golang.org/protobuf v1.0.0
 )

cmd/protoc-gen-go/testdata/go.mod

@@ -1,7 +1,7 @@
-module google.golang.org/protobuf/v2/cmd/protoc-gen-go/testdata
+module google.golang.org/protobuf/cmd/protoc-gen-go/testdata
 
 require (
-	github.com/golang/protobuf v1.2.1-0.20190509013249-911a20d79252
+	github.com/golang/protobuf v1.2.1-0.20190514181236-7800af189d76
 	google.golang.org/protobuf v1.0.0
 )
 

go.mod

@@ -0,0 +1,8 @@
+module google.golang.org/protobuf
+
+go 1.9
+
+require (
+	github.com/golang/protobuf v1.2.1-0.20190514181236-7800af189d76
+	github.com/google/go-cmp v0.3.0
+)

go.sum

@@ -0,0 +1,5 @@
+github.com/golang/protobuf v1.2.1-0.20190514181236-7800af189d76 h1:V0/EhMNrdv06pDVp7kn2tsFO8WE9T3zJamTPeb4QgLg=
+github.com/golang/protobuf v1.2.1-0.20190514181236-7800af189d76/go.mod h1:Zfz6qcDoDBESdv6JsKsGpgNHnkvwJAJwcA9eL+mOkgc=
+github.com/google/go-cmp v0.3.0 h1:crn/baboCvb5fXaQ0IJ1SGTsTVrWpDsCWC8EGETZijY=
+github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
+google.golang.org/protobuf v0.0.0-20190514172829-e89e6244e0e8/go.mod h1:791zQGC15vDqjpmPRn1uGPu5oHy/Jzw/Q1n5JsgIIcY=