Use stdlib context in generated Go files (#4904)

grpc/src/compiler/go_generator.cc

@@ -84,7 +84,7 @@ void GenerateImports(grpc_generator::File *file, grpc_generator::Printer *printe
 	}
 	printer->Print("import (\n");
 	printer->Indent();
-	printer->Print(vars, "$context$ \"golang.org/x/net/context\"\n");
+	printer->Print(vars, "$context$ \"context\"\n");
 	printer->Print(vars, "$grpc$ \"google.golang.org/grpc\"\n");
 	printer->Outdent();
 	printer->Print(")\n\n");

grpc/tests/go_test.go

@@ -3,10 +3,10 @@ package testing
 import (
 	"../../tests/MyGame/Example"
 
+	"context"
 	"net"
 	"testing"
 
-	"golang.org/x/net/context"
 	"google.golang.org/grpc"
 )
 

tests/MyGame/Example/MonsterStorage_grpc.go

@@ -7,7 +7,7 @@ package Example
 import "github.com/google/flatbuffers/go"
 
 import (
-  context "golang.org/x/net/context"
+  context "context"
   grpc "google.golang.org/grpc"
 )