fix anon-struct usage that's a warning/error -Wnon-c-typedef-for-linkage (#137)

Summary:
X-link: facebook/CacheLib#137

Fix
  error: anonymous non-C-compatible type given name for linkage purposes by alias declaration; add a tag name here [-Werror,-Wnon-c-typedef-for-linkage]

Reviewed By: philippv

Differential Revision: D36043476

fbshipit-source-id: df3fa684c8655184dd8f87045542cd7f5704a65e

Author: luciang

gloo/broadcast_one_to_all.h

@@ -118,7 +118,7 @@ class BroadcastOneToAll : public Algorithm {
   const int rootPointerRank_;
 
   // For the sender (root)
-  using forSender = struct {
+  struct forSender {
     int dummy;
     std::unique_ptr<transport::Buffer> clearToSendBuffer;
     std::unique_ptr<transport::Buffer> sendBuffer;
@@ -127,7 +127,7 @@ class BroadcastOneToAll : public Algorithm {
   std::vector<std::unique_ptr<forSender>> sender_;
 
   // For all receivers
-  using forReceiver = struct {
+  struct forReceiver {
     int dummy;
     std::unique_ptr<transport::Buffer> clearToSendBuffer;
     std::unique_ptr<transport::Buffer> recvBuffer;

gloo/cuda_broadcast_one_to_all.h

@@ -52,7 +52,7 @@ class CudaBroadcastOneToAll : public Algorithm {
   const bool synchronizeDeviceOutputs_;
 
   // For the sender (root)
-  using forSender = struct {
+  struct forSender {
     int dummy;
     std::unique_ptr<transport::Buffer> clearToSendBuffer;
     std::unique_ptr<transport::Buffer> sendBuffer;
@@ -61,7 +61,7 @@ class CudaBroadcastOneToAll : public Algorithm {
   std::vector<std::unique_ptr<forSender>> sender_;
 
   // For all receivers
-  using forReceiver = struct {
+  struct forReceiver {
     int dummy;
     std::unique_ptr<transport::Buffer> clearToSendBuffer;
     std::unique_ptr<transport::Buffer> recvBuffer;