THRIFT-4984: Handle wrapped io.EOF errors

TCompactProtocol (which is used by THeaderTransport to read headers)
could wrap the underlying error with TProtocolException, which breaks
err == io.EOF test in some cases.

Client: go

This closes #1922.
diff --git a/lib/go/thrift/simple_server.go b/lib/go/thrift/simple_server.go
index aa5a6a6..756d4cf 100644
--- a/lib/go/thrift/simple_server.go
+++ b/lib/go/thrift/simple_server.go
@@ -221,7 +221,9 @@
 	if err == nil {
 		return nil
 	}
-	if err == io.EOF {
+	// err could be io.EOF wrapped with TProtocolException,
+	// so that err == io.EOF doesn't necessarily work in some cases.
+	if err.Error() == io.EOF.Error() {
 		return nil
 	}
 	if err, ok := err.(TTransportException); ok && err.TypeId() == END_OF_FILE {