No NCCL on macOS (#11652)

* Make paddle no longer depend on boost

* Update enforce.h

paddle/fluid/platform/dynload/CMakeLists.txt

 cc_library(dynamic_loader SRCS dynamic_loader.cc DEPS glog gflags enforce)
 
-list(APPEND CUDA_SRCS cublas.cc cudnn.cc curand.cc nccl.cc)
+list(APPEND CUDA_SRCS cublas.cc cudnn.cc curand.cc)
+
+# There is no macOS version of NCCL.
+if (NOT APPLE)
+  list(APPEND CUDA_SRCS nccl.cc)
+endif()
+
 if (TENSORRT_FOUND)
   list(APPEND CUDA_SRCS tensorrt.cc)
 endif()
 
-
 configure_file(cupti_lib_path.h.in ${CMAKE_CURRENT_BINARY_DIR}/cupti_lib_path.h)
 if (CUPTI_FOUND)
     list(APPEND CUDA_SRCS cupti.cc)

paddle/fluid/platform/enforce.h

@@ -44,8 +44,10 @@ limitations under the License. */
 #include "paddle/fluid/platform/dynload/cublas.h"
 #include "paddle/fluid/platform/dynload/cudnn.h"
 #include "paddle/fluid/platform/dynload/curand.h"
+#ifndef __APPLE__
 #include "paddle/fluid/platform/dynload/nccl.h"
-#endif
+#endif  // __APPLE__
+#endif  // PADDLE_WITH_CUDA
 
 namespace paddle {
 namespace platform {
@@ -174,6 +176,7 @@ inline typename std::enable_if<sizeof...(Args) != 0, void>::type throw_on_error(
   throw std::runtime_error(err + string::Sprintf(args...));
 }
 
+#ifndef __APPLE__
 template <typename... Args>
 inline typename std::enable_if<sizeof...(Args) != 0, void>::type throw_on_error(
     ncclResult_t stat, const Args&... args) {
@@ -184,7 +187,7 @@ inline typename std::enable_if<sizeof...(Args) != 0, void>::type throw_on_error(
                              string::Sprintf(args...));
   }
 }
-
+#endif  // __APPLE__
 #endif  // PADDLE_WITH_CUDA
 
 template <typename T>