message: Fix compilation failure with RDMA+GDR
  This fix tries to address the issue raised in 21696 where
  tensorflow failed to compile when both RDMA and GDR are on.
  The issue is that the memory allocator of GDR used the same
  name as RDMA.
  This fix fixes 21696.
diff: @@ -186,22 +186,22 @@ class GdrMemoryManager : public RemoteMemoryManager {
  // TODO(byronyi): remove this class and its registration when the default
  // cpu_allocator() returns visitable allocator, or cpu_allocator() is no
  // longer in use.
  -class BFCRdmaAllocator : public BFCAllocator {
  +class BFCGdrAllocator : public BFCAllocator {
  public:
  - BFCRdmaAllocator()
  + BFCGdrAllocator()
  : BFCAllocator(new BasicCPUAllocator(port::kNUMANoAffinity), 1LL << 36,
  true, "cpu_rdma_bfc") {}
  };
  -class BFCRdmaAllocatorFactory : public AllocatorFactory {
  +class BFCGdrAllocatorFactory : public AllocatorFactory {
  public:
  - Allocator* CreateAllocator() override { return new BFCRdmaAllocator; }
  + Allocator* CreateAllocator() override { return new BFCGdrAllocator; }
  virtual SubAllocator* CreateSubAllocator(int numa_node) {
  return new BasicCPUAllocator(numa_node);
  }
  };
  -REGISTER_MEM_ALLOCATOR("BFCRdmaAllocator", 101, BFCRdmaAllocatorFactory);
  +REGISTER_MEM_ALLOCATOR("BFCGdrAllocator", 101, BFCGdrAllocatorFactory);
  GdrMemoryManager::GdrMemoryManager(const string& host, const string& port)
  : host_(host),
  